Great Lakes Fishery Resources Restoration Study - US Fish and ...

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Report to Congress

Great Lakes Fishery Resources Restoration Study

Report

U .S . Fish and Wildlife Service Department of Interior Prepared by U.S. Fish and Wildlife Service Great Lakes Coordination Office Great Lakes Fishery Resources Offices Dale P. Burkett - Overall Study Manager/Report Editor Wolf-Dieter N Busch - Lake Ontario & Lake Erie Study Manager Ferry R . McClain - Lake Huron Study Manager Mark E. Holey - Lake Michigan Study Manager Thomas R . Busiahn - Lake Superior Study Manager May C. Fabrizio - Fish Community Dynamics Researcher, National Biological Service, Great Lakes Science Center

Acknowledgements The Service gratefully acknowledges our Bad River Tribal Council, Bay Mills Indian, Community of Michigan, Chippewa-Ottawa Treaty Fishery Management Authority, Grand Portage Reservation, Grand Traverse Band of Ottawa and Chippewa Indians, Great Lakes Fishery Commission, Great Lakes Commission, Great Lakes Indian Fish and Wildlife Commission, Illinois Department of Natural Resources, Indiana Department of Natural Resources, Keweenaw Bay Indian Community, Michigan Department of Natural Resources, Minnesota Department of Natural Resources, New York State Department of Environmental Conservation, Ohio Department of Natural Resources, Pennsylvania Fish and Boat Commission, Red Cliff Band of Lake Superior Chippewa Indians, Sault Ste . Marie Band of Chippewa Indians, U.S . Army Corps of Engineers, U.S. Environmental Protection Agency-Great Lakes National Program Office, U .S. National Biological Service-Great Lakes Science Center, and Wisconsin Department of Natural Resources partners for assistance in contributing information to and reviewing drafts of this document and for their many helpful comments and suggestions. Without the tireless, selfless, and dedicated efforts of Service staff in the Great Lakes Coordination Office and the Lower Great Lakes, Alpena, Green Bay, and Ashland Fishery-Resources Offices, this report could not have been completed .

United States Department of the Interior FISH AND WILDLIFE SERVICE Washington, D .C . 20240 IN REPLY REFER TO,

SEP 13 1995

FWSIMA

The Honorable Albert Gore, Jr. President of the Senate Washington, D.C. 20510 Dear Mr. President: We are pleased to submit the Great Lakes Fishery Resources Study that was undertaken pursuant to Section 2005(a) of the Great Lakes Fish and Wildlife Restoration Act, P .L . 101-537. This report focuses on the status of fishery resources and habitat in the Great Lakes Basin including the effectiveness of present management plans, and analysis of the impacts and management control alternatives for recently introduced nonindigenous species . Recommendations have been developed regarding those actions necessary to restore the fishery resources of the Great Lakes Basin to sustainable levels . Please do not hesitate to contact our office if you have any questions or comments . Sincerely,

' Director

Enclosure

United States Department of the Interior FISH AND WILDLIFE SERVICE Washington, D .C . 20240 I N REPLY REFER TO .

FWS/MA

SEP t 3 1995

The Honorable Newt Gingrich Speaker of the House of Representatives Washington, D.C. 20510 Dear Mr . Speaker: We are pleased to submit the Great Lakes Fishery Resources Study that was undertaken pursuant to Section 2005(a) of the Great Lakes Fish and Wildlife Restoration Act, P .L. 101-537. This report focuses on the status of fishery resources and habitat in the Great Lakes Basin including the effectiveness of present management plans, and analysis of the impacts and management control alternatives for recently introduced nonindigenous species . Recommendations have been developed regarding those actions necessary to restore the fishery resources of the Great Lakes Basin to sustainable levels . Please do not hesitate to contact our office if you have any questions or comments . Sincerely,

. Director

Enclosure

Contents;

Table of Contents

awn

LakeOntarti

Executive Summary

vi

Findings and Recommendations

viii

ntroduction Purpose of the Document

1

Great Lakes Fish and Wildlife Restoration Act Historic perspective Background information Purposes of the Act

1 1 1 2

Great Lakes Fishery Resources Restoration Study Study objectives Development of proposals

Historic and Current Status of Fishery Resource and Trends 32 Offshore fish community 32 Nearshore/tributary fish community 47 Causes of Changes in Lake Ontario Fishery Resources and Management Strategies Physical factors Chemical factors Biological factors

56

56 59 59

3

3 4

Great Lakes Basin Description Great Lakes climate Physiographics, hydrographics, and trophic state Socioeconomics Ecosystem Approach

Trophic Guild Analyses 31 Trophic guild definitions .. . 31 Limitations to using commercial data 32

5

5 5 15

4.6

Ecosystem Health Concepts

20

Support for the Ecosystem Approach

21

Setting Ecosystem Goals and Objectives

22

Lake Ontario : An Ecosystem Approach Case Example Habitat classification methodology Lake Ontario tributary habitats

22

23 27

Historic and Current Status of Fishery Resource and Trends 69 Offshore fish community 69 Nearshore/tributary fish community 76 Causes of Changes in Lake Erie Fishery

Resources and Management Strategies Physical factors Chemical factors Biological factors

90

90 91 93

Historic and Current Status of Fishery 100 Resource and Trends Offshore fish community 102 Nearshore fish community 110 Nearshore fish community-warmwater bays 112 Causes of Changes in Lake Huron Fishery Resources and Management Strategies Causes of changes in Lake Huron fishery resources Management strategies in Lake Huron

113 113 113



ii

inA, i a fWaluatom of istiing° Historic and Current Status of Fishery Resource and Trends Offshore fish community Nearshore fish community

Maag `mment .'' it' .'.s;imp?* Plans eA /~`?..

115 116 120

Causes of Changes in Lake Michigan Fishery Resources and Management Strategies 122 Causes of changes in Lake Michigan fishery resources 122 Management strategies in Lake Michigan 124

Historic and Current Status of Fishery Resource and Trends Offshore fish community Inshore fish community Nearshore fish community Tributary fish community

125 125 128 129 131

Causes of Changes in Lake Superior Fishery Resources and Management Strategies 131 Causes of changes in Lake Superior fishery resources 131 Management strategies in Lake Superior 135 Basin wide Researcl oa Fish ~ ► Citica Evaluation of Histor OtData

PopulattnDynaic~

Restoration Ecology of Lake Trout

139

Dynamics of Great Lakes Forage-fish Communities

141

Community Dynamics of Commercially-harvested Fishes

145

Interagency Fishery Management Plans 148 Fish management planning 148 Coordinated fishery management 149 Ecosystem Partnership Coordination

Philosophical, Ethical, and Decision-making Considerations Lack of historic knowledge and expertise Changing ethos Decision-making and public expectations

150

151 151 151 152

Effects of Impediments to Ecosystem Restoration

153

Examples of Impediments Restoring a Healthy Ecosystem

153 157 172

111

Contents

List of Figures Figure 1 .

Appropriations and authorized funding levels for the Great Lakes Fish and Wildlife Restoration Act of 1990 .

vii

Figure 2 .

Map illustrating the Great Lakes watershed.

5

Figure 3 .

Map illustrating the four basins of Lake Ontario .

5

Figure 4.

Map illustrating the three basins of Lake Erie .

8

Figure 4a .

Lake Huron contours .

9

Figure 5 .

Lake Michigan contours .

11

Figure 6 .

Lake Superior contours.

12

Figure 7 .

Conceptual representation of the degradation of an ecosystem and the recovery due to restoration initiatives .

22

Figure 8 .

Dichotomous Key scores by stress category for Lake Ontario .

26

Figure 9 .

Total riverine habitat(km) in five U .S. Lake Ontario tributaries impacted by the construction of dams .

28

Figure 10 .

Percent composition of habitat available to fishes in five U .S . Lake Ontario tributaries up to the first impassible barrier .

29

Figure 11 .

Free-flowing riverine habitat (km) available to migrating fishes in five Lake Ontario tributaries .

30

Figure 12 .

Offshore trophic fish communities (guilds) for Lake Ontario .

34

Figure 13 .

Trends in the Lake Ontario offshore planktivorous guild, as represented by commercial harvest records .

34

Figure 14 .

Annual commercial harvest of rainbow smelt from Lake Ontario .

35

Figure 15 .

Changes in total phosphorous and zooplankton production in Lake Ontario .

36

Figure 16 .

Biomass index of alewife and smelt in Lake Ontario .

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Figure 17 .

Trawl indices of abundance for the largest alewife and smelt in Lake Ontario .

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Figure 18.

Trends in the Lake Ontario offshore macroinvertivorous guild .

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Figure 19.

Commercial catch of Lake Ontario lake whitefish .

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Figure 20 .

Standard gillnet indices of abundance for lake whitefish in Lake Ontario .

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Figure 21 .

Trends in the Lake Ontario offshore indigenous piscivorous guild .

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Figure 22 .

Annual commercial harvest of blue pike and walleye from Lake Ontario .

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Figure 23 .

Millions of indigenous and nonindigenous piscivorous fish stocked annually in Lake Ontario .

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Figure 24 .

Trends in the Lake Ontario nearshoreltributary trophic fish communities (guilds) for Lake Ontario .

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Figure 25 .

Trend of the Lake Ontario nearshoreltributary, omnivorous guild .

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Figure 26 .

Abundance index of omnivorous fishes in Lake Ontario tributaries.

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Figure 27 .

Abundance index of gizzard shad and golden shiner .

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Figure 28 .

Abundance index of macroinvertivorous fishes in Lake Ontario tributaries .

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Figure 29 .

Trend in U.S .Lake Ontario tributary, macroinvertivorous guild .

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Figure 30 .

Trends in the Lake Ontario nearshoreltributary, piscivorous guild .

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Figure 31 .

Abundance index of piscivorous fishes in Lake Ontario tributaries .

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Figure 32 .

Numbers of American eel caught at the R .H . Saunders dam eel ladder, St . Lawrence River, Quebec.

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Figure 33 .

Lake Ontario empirical and predicted winter water temperatures .

58



iv

Contents,

Figure 34 .

Number of nonindigenous aquatic species introductions into the Great Lakes .

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Figure 35 .

Number and type of nonindigenous aquatic species introduced into the Great Lakes .

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Figure 36 .

Introduction pathways for nonindigenous aquatic species in the Great Lakes,

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Figure 37 .

Production of trophic guilds in three time periods based on commercial harvest data .

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Figure 38 .

Annual commercial harvest of lake herring and rainbow smelt from Lake Erie .

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Figure 39 .

Annual commercial harvest in Canadian waters of rainbow smelt, in Lake Erie .

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Figure 40.

Annual commercial harvest of lake whitefish from Lake Erie .

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Figure 41 .

Annual commercial harvest of blue pike and other species of the offshore piscivorous guild from Lake Erie .

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Figure 42 .

Lake trout abundance in eastern basin Lake Erie .

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Figure 43 .

Lake trout abundance compared to annual commercial catch of sea lamprey from Lake Erie .

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Figure 44 .

Nearshore trophic fish communities (guilds) for Lake Erie .

77

Figure 45 .

Trends in the Lake Erie nearshore omnivorous guild .

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Figure 46 .

Index of abundance for several nearshore omnivore guild species in the western basin of Lake Erie .

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Figure 47 .

Representative index of abundance for spottail shiners .

79

Figure 48 .

Index of abundance for gizzard shad in the western basin of Lake Erie .

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Figure 49 .

Representative indices of abundance for emerald shiner in the western basin and the central basin, in Lake Erie .

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Figure 50 .

Trends in the Lake Erie nearshore macroinvertivore guild species .

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Figure 51 .

Trends in the Lake Erie nearshore macroinvertivore guild species .

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Figure 52 .

Lake Erie yellow perch population size estimated using CAGEAN model .

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Figure 53 .

Representative indices of abundance for white perch in Lake Erie .

85

Figure 54 .

Representative indices of abundance for white bass in Lake Erie .

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Figure 55 .

Trends in the Lake Erie nearshore piscivorous guild .

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Figure 56 .

Walleye Commercial fishery catch per unit effort (CPUE) compared to angler CPUE for walleye in Lake Erie .

88

Figure 57 .

Smallmouth bass indices of abundance (CPUE) in the western and eastern basins of Lake Erie .

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Figure 58 .

Number of adult and larval fish species identified in the lower 12 .8km (8 mi) of the Buffalo River .

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Figure 59 .

Mean abundance (May to November) of zebra mussel veligers in the western and west-central basins of Lake Erie .

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Figure 60 .

Mean annual secchi disk transparency (m) for New York waters of Lake Erie .

96

Figure 61 .

Map of the Lake Huron basin showing statistical districts with U .S . and Canadian points of reference.

100

Figure 62 .

Annual commercial harvest of principal Lake Huron fish species .

101

Figure 63 .

Biomass of alewife, rainbow smelt and bloater chub in Michigan waters of Lake Huron .

102

Figure 64 .

Annual commercial harvest of coregonines from Lake Huron .

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Figure 65 .

Total catch per unit of effort (CPUE) for three strains of lake trout captured during fall spawning surveys on Six Fathom Bank .

106

Average sea lamprey wounding on various sizes of lake trout .

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Figure 66 .



V

Figure 67 .

Millions of predator fish stocked annually in Lake Huron.

107

Figure 68 .

Annual harvest of the major commercial fish species from Lake Michigan.

115

Figure 69 .

Forage biomass in Lake Michigan.

117

Figure 70.

Harvest of the major sport fish species from Lake Michigan.

119

Figure 71 .

Millions of trout and salmon stocked annually in Lake Michigan.

119

Figure 72 .

Map of Lake Michigan illustrating lake trout rehabilitation zones .

121

Figure 73.

Percent weight composition of diet items for lake trout, coho salmon, chinook salmon, brown trout and rainbow trout .

123

Figure 74.

Annual commercial harvest of offshore fishes from Lake Superior .

126

Figure 75.

Annual commercial harvest of select inshore fishes from Lake Superior .

129

Figure 76 .

Annual commercial harvest of nearshore fishes from Lake Superior .

130

Figure 77 .

Probability of tag shedding for three types of anchor tags used to tag individual lake trout .

141

Figure 78 .

Time series of annual mean air temperature for six stations around Lake Michigan .

144

Figure 79 .

Relative abundance of bloater as indicated by bottom trawl surveys at eight ports .

144

Figure 80 .

Relative abundance of alewife as indicated by bottom trawl surveys at eight ports .

145

vi:,

4a_

JJr

List of Tables

Table 1 .

Great Lakes physiographic and hydrographic features.

Table 2 .

The hierarchy of aquatic habitat classification (modified from Sly and Busch 1992b).

23

Table 3 .

Estimated anthropogenic impairments (stresses) affecting habitat functions in Lake Ontario.

25

Table 4 .

List of select fish species from Lake Ontario offshore habitats according to trophic guild.

33

Table 5 .

List of select fish species from Lake Ontario nearshoreltributary habitats according to trophic guild.

47

Table 6 .

Colonial nesting birds on man-made natural sites in the U .S . Great Lakes.

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Table 7 .

List of select fish species from Lake Erie offshore habitats according to trophic guild.

69

Table 8 .

List of select fish species from Lake Erie nearshoreltributary habitats according to trophic guild.

76

Table 9 .

Effects of extractive land uses on the nearshore fish community of Lake Superior.

134

Table 10 .

Effects of industrial land uses on the nearshore fish community of Lake Superior.

134

Table 11 .

Effects of transportation and social land uses on the nearshore fish community of Lake Superior.

135

Table 12 .

Commercially-important species in the Great Lakes .

146

6

Appendices Appendix I Summary of Recommendations

174

Appendix II Great Lakes Fishes Status and Trends

178

Appendix III Statutory Mandates and Authorities

185

Appendix IV Great Lakes Fish and Wildlife Restoration Act of 1990

188

Appendix V Memorandum of Understanding for the Coordination and Joint Implementation of the Great Lakes Fish and Wildlife Restoration Act of 1990

193

v1

Executive Summary

The Great Lakes Fish and Wildlife Restoration Act (1990), hereafter called the Act, outlines activities that the U .S . Fish and Wildlife Service (Service) and the Corps of Engineers will undertake to assist the management, protection, and restoration of the natural resources of the interjurisdictional, binational basin of the Great Lakes . The Great Lakes Fishery Resources Restoration Study (Study) presented in this report is one of the required activities of the Act . The Act includes recognition that the system is addressed by many institutions, is large, and is ecologically complex.

Management, protection, and restoration of Great Lakes resources provides unique challenges . One of the challenges involves the size, more comparable to oceans than lakes, resulting in the need to use research tools such as "ocean type" vessels . Scientific challenges include questions concerning the applicability of site specific data to understand natural resource problems at the sub-basin, basin, or whole lake level, since jurisdictional field investigations are often Iimited to their home area and natural resources are not limited by political boundaries . Other challenges are the maintenance of costly, long-term, data collection programs and the use and compatibility of data from various sources and time periods to understand ecosystem health trend analyses.

The U.S . Federal, Native American Tribal, and State governments have collaborated to jointly initiate projects to better understand and rehabilitate the ecosystem . The States have primary jurisdiction over resident fish and wildlife in the Great Lakes Basin and human activities affecting these species . The Service conducts activities under numerous Federal authorities that generally relate to migratory and interjurisdictional species and habitat . Such laws include, but are not limited to the Fish and Wildlife Act of 1956, Endangered Species Act, Migratory Bird Treaty Act, and the Nonindigenous Aquatic Nuisance Prevention and Control Act (see Appendix III) . The U.S . Federal government has negotiated bi-national treaties concerning the Great Lakes. These treaties provide for international cooperation between the U .S . and Canadian Federal governments . Protection of bi-national ecosystem health is a Federal role in the Boundary Waters Treaty (1909).

Several Native American tribal governments have treaties with the United States, through which they retained rights to harvest fish and, in some cases wild game and other natural resources, in ceded territories . These Native American Tribes have implemented management programs to regulate their harvest, restore, and enhance natural resources, and coordinate with State and U .S. and Canadian Federal governments. Native American Tribes, as active partners in management of the Great Lakes, bring a unique and valuable perspective that is based on their long history, pre-dating that of the U .S . and Canada, and their strong ethic for conserving resources for the "Seventh Generation".



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The Act provides the basis for agencies of the U .S . Federal government to work in partnership with Great Lakes States and Native American Tribes and to address resource management problems of the bi-national basin . The Act also provides for coordination of U .S. Federal activities . The Act became law in November, 1990, and limited funds have been appropriated since Fiscal Year 1992 (Figure 1) . Efforts were made to use these funds to address completion of the Study, conduct specific restoration projects, provide additional scientific information upon which to conduct management actions, provide fiscal/partnership support, and enhance coordination activities between State, Native American Tribal, and Federal agencies. This report details the results of the Study and makes specific Findings and Recommendations which immediately follow the Executive Summary for the convenience of the reader . These Findings and Recommendations are based upon information contained in the body of the Study report and the Recommendations are summarized in tabular format in Appendix I. Great Lakes fish species status and trends are subjectively summarized in Appendix II, providing a current overview of the status of knowledge, or lack thereof, of fish communities of the Great Lakes Basin. This information will be updated in future biennial reports to Congress on progress made with respect to the Act.

Implementation of Study recommendations will enable careful management of the living resources of the Great Lakes, ensuring maximum public benAppropriated / Authorized efit and guaranteeing perpetuation of 12 / these resources. Agreed upon goals and r if 14 objectives of international cooperative . efforts in the Great Lakes Basin between the U.S. and Canada will be realized as the health of fish and wild life resources improves . When viable 2 _ and productive stocks of native and other desired fish species are available, 1991 1992 1993 1994 1995 bald eagles successfully reproduce and Federal Fiscal Year inhabit shorelines, mink and otter once Figure 1 . Appropriations and authorized funding levels for again claim their habitat, chemical the Great Lakes Fish and Wildlife Restoration Act of 1990, and other stress-induced deformities in fish and wildlife are eliminated, and fish and wildlife can be consumed with little or no risk to human health, then restoration goals for the Great Lakes Basin will have been met.

Findings

Findings and Recommendations Findings Basin-wide findings Restoring the Great Lakes ecosystem, home for 10 percent of the U .S ., and 25 percent of the Canadian populations, to a condition that meets the needs identified by society, will require that increased efforts be undertaken, both to quantify these needs and to address them . Working under the cooperatively developed guidance of the Strategic Plan for Management of Great Lakes Fisheries (Great Lakes Fishery Commission 1980) and the Great Lakes Water Quality Agreement, State, Provincial, Native American Tribal, and Federal agencies bordering the Great Lakes have made significant progress toward the goal of restoring a healthy fish community to the lakes . These resource agencies are working under budget constraints and only the highest priority activities are undertaken . Much of what has been gained could be lost without adequate support . The Act authorizes increased funding for resource agencies to address the most pressing needs in the Great Lakes. Restoration of the Great Lakes is a complex process requiring the cooperation of local, City, County, State, Provincial, Native American Tribal and Federal agencies in addition to many conservation and public interest groups. Within a governmental agency, there can often be dramatic differences in how the resource management and environmental sections of the agency approach Great Lakes issues . In the future, environmental and fish managers must overcome substantial challenges . Differences in mandate, perception of priorities, and style of management create major institutional impediments to systematic and comprehensive coordination of ecosystem management . Many of the current problems are, in fact, the unintended consequences of uncoordinated management of water quality, fisheries, shipping, and human developments in the Great Lakes Basin . Concepts of responsible resource use and management and biological conservation should not be at odds, but should be integrated via partnerships to meet future needs . Information exchange and cross program forums should be established to encourage management and environmental policies to be endorsed as one. Although coordination of water quality and fish management is necessary for progress in implementing ecosystem management, it is not sufficient . Water quality and fish management issues are themselves imbedded in a hierarchy of other management decision-making and social and economic developments . It is important to recognize that a systematic and comprehensive approach to the restoration of the ecosystems of the Great Lakes requires joining ecological restoration and human development at spatial and temporal scales that are beyond human experience . The integrity of the Great Lakes ecosystems is affected by activities far outside the basin.

Lake Ontario findings The Lake Ontario ecosystem has undergone significant declines in productivity during the 1980s that parallel reductions in phosphorous concentrations ; resulting in a return to an oligotrophic lake trophic level . Prey fish (alewife and rainbow smelt) production and biomass levels are declining . This predator/prey imbalance is leading to reductions in predator survival and growth, which have caused managers to change their stocking strategies by reducing stocking levels in 1993 and 1994 . However, water quality improvements, reduced exploitation and recent reductions in alewife and rainbow smelt have increased the feasibility of restoring ciscoes and sculpins, the once major components of the prey fish community in Lake Ontario . The restoration of these species is a significant element of current and future restoration plans for indigenous top predators, such as lake trout and Atlantic salmon .

Findings

Lake Ontario's lake trout population disappeared due to habitat degradation and overexploitation . Lake trout restoration is currently progressing; however, numerous information gaps remain, limiting further advancement . According to the existing Draft Lake Ontario Lake Trout Rehabilitation Plan - 1990 Revision, by the Lake Trout Technical Committee of the Lake Ontario Committee, Great Lakes Fishery Commission, issues expected to affect lake trout rehabilitation in Lake Ontario within the next decade fall into three groups : (1) spawning dynamics and early life history ; (2) spawning and nursery habitat; and (3) population maintenance and fish community interactions. Atlantic salmon were extirpated from Lake Ontario in the late 1800s . As interest and involvement in Atlantic salmon restoration increases, it is necessary to assess and prioritize historic spawning tributaries, potential habitat, and current impairments to Atlantic salmon restoration . A total of 200,000 Atlantic salmon fry are allocated for annual stocking in Lake Ontario, but this target has not been met due to the lack of availability of fish. This target could be met, if feasibility studies relating to the establishment of Atlantic salmon populations in Lake Ontario tributaries were incorporated with restoration efforts . Limited feasibility studies are currently addressing survival, reproduction, and recruitment . Other issues limiting restoration include : development of a large scale Atlantic salmon broodstock and production program ; and addressing genetics, fish health, product evaluation, and rearing and instream flow requirements. An abundance of data have been collected, are available and continue to be compiled to describe past changes and current conditions in Lake Ontario . However, research addressing other critical components within the system is not being conducted . Habitat concerns in Lake Ontario encompass the physical, chemical and biological environment required to support the aquatic community . Limited abundance, distribution and productivity of species, and poor habitat quality and quantity are obstacles to restoring and maintaining the aquatic community . Protection and restoration of sensitive habitats such as spawning and nursery grounds, and improved upstream and downstream passage are critical issues requiring action. The recent recognition of the need to revise the Fish Community Goals and Objectives for Lake Ontario by the agencies charged with management of the lake is an important step in designing the future direction of restoration of a healthy ecosystem in Lake Ontario. Beyond the scope of the individual species involved, the Fish Community Goals and Objectives for Lake Ontario address concurrently important issues such as habitat and genetic integrity . Many of the identified fishery management needs are already ongoing such as lake trout restoration recovery plans; others, such as lake sturgeon recovery plans and an Atlantic salmon broodstock program, are currently being initiated. The Lake Ontario basin and its aquatic resources provide great opportunities . Long-term maintenance should focus on an ecosystem approach in order to preserve and enhance the current habitat resources in the basin.

Lake Erie findings Lake Erie is highly susceptible to environmental changes because of its shallowness, low water volume, and its location among the Great Lakes. Changes are rapid and involve the majority of the lake since the shallow nearshore area comprises over 80% of the total surface area . Implementation of phosphorus abatement programs over the past two decades has been a success in reducing the overall productivity of the system and eliminating algal blooms and fish kills . However, continuing improvement in water quality may result in a less productive system . Fish community structure is expected to change and productivity is expected to decline as system productivity declines . These less productive conditions may favor a return of indigenous fish species indicative of oligotrophy, such as lake herring and lake whitefish. A general lack of information exists on the nearshore fish community . Information exists for the economically and recreationally important walleye, smallmouth bass, and yellow perch which have been monitored regularly by the

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States since the 1970s . While these three species have generally been targets for monitoring programs, some information on other species has been collected . Monitoring assessments employ different gear throughout the lake making it difficult to compare or combine information . Attempts have been made to combine data for walleye and yellow perch to estimate population size using the CAGEAN model, but results are questionable . Causes of many of the current trends are unknown. An ecosystem approach to monitoring of the aquatic community is required . Such an approach would include monitoring nutrient levels and lower trophic levels such as phytoplankton and zooplankton populations . A monitoring program for zooplankton has been initiated, but needs to be made current . Monitoring programs need to be expanded to other trophic levels. Improvements in the water quality of Areas of Concern, such as in the Buffalo River, have allowed fish and wildlife to return . However, impairments to complete restoration still exist . Beneficial use impairments include : restrictions on fish and wildlife consumption ; dissolved oxygen depletion ; existence of fish tumors and other deformities ; contaminated sediments ; degradation of the benthos ; and loss of fish and wildlife habitat. Human activities have destroyed many important habitats within the basin . Remaining habitats important to fish and wildlife as feeding, breeding, nesting, spawning and nursery areas may still be in danger of destruction. The recent development of draft Fish Community Goals and Objectives for Lake Erie by the agencies charged with management of the lake is an important step in designing the future direction of restoration of a healthy ecosystem in Lake Erie . Beyond the scope of the individual species involved, the Fish Community Goals and Objectives for Lake Erie address concurrently important issues such as habitat and genetic integrity . Many of the identified fishery management needs are already ongoing, such as lake trout restoration recovery plans, and others including Lake sturgeon recovery plans are currently being initiated.

Lake Huron findings With the exception of regions near population centers such as inner Saginaw Bay and Georgian Bay, the limnological condition of Lake Huron has changed very little since the 1800s . It remains a deep oligotrophic lake. The fish community of the lake, however, has undergone dramatic change due to a number of factors . Over-exploitation, habitat loss and degradation and introduction of nonindigenous fish species have combined to cause alterations that, in many cases, are irreversible. Historically, Lake Huron ranks third among the Great Lakes in commercial fish production . Lake trout and lake herring ranked one and two in total catch through 1940 . Although excessive harvest coupled with degraded water quality and habitat alteration depressed lake trout stocks in many locations, the introduction of sea lamprey led to the final collapse of lake trout in Lake Huron . Eutrophication of Saginaw Bay, a primary production area for lake herring in the main basin, was a major contributor to the collapse of lake herring populations . Innovations in commercial fishing gear added further pressures to a declining Lake Huron fish community . The introduction and use of the deep-water trap net is thought to be a major contributor to the collapse of the lake whitefish fishery in Lake Huron. The introduction of nonindigenous species such as alewife and rainbow smelt further aggravated the increasing instability of the Lake Huron fish community . In some cases the nonindigenous players simply filled voids created by lost stocks, and flourished . In other cases they directly competed with indigenous species and assisted in declines of those stocks .

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In all, the present day fish community and the food web that drives the system only vaguely resembles that of the early 1800s . This is not to say, however, that all changes have been negative. Active fishery management, necessitated by the declining health of the system, has led to a far better understanding of the interaction between individual components of the ecosystem, and, in many cases, to recovery of some species . Much work remains, however, before stability can be returned to the system. The recent development of Fish Community Goals and Objectives for Lake Huron by the agencies charged with management of the lake is an important first step in describing a healthy ecosystem in Lake Huron . Beyond the scope of the individual species involved, the Fish Community Goals and Objectives for Lake Huron address important issues such as habitat and genetic integrity . Many of the identified fishery management needs are ongoing, such as lake trout rehabilitation, whereas others, including lake sturgeon recovery plans, are currently being initiated . Unfortunately, the needs far outweigh existing capabilities.

Lake Michigan findings Historically, Lake Michigan was the most productive of the oligotrophic Great Lakes in terms of yield to the commercial fishery. The indigenous fish community that supported that yield was drastically altered by the invasion of nonindigenous species such as sea lamprey and alewife, heavy fishing pressure, and habitat degradation . Indigenous species such as lake sturgeon stocks were drastically reduced in the early 1920s from over exploitation and habitat degradation ; lake trout stocks were extirpated in the 1950s with the dramatic increase in sea lamprey abundance ; and yellow perch, lake herring, burbot and bloater, declined precipitously in the 1960s following the explosion of alewife. By the 1960s, alewife comprised up to 80 percent of the total fish biomass in Lake Michigan . They died and washed up in great numbers, leaving a smelly rotten odor along shorelines and beaches, because the lake could not support that level of alewife biomass . Chinook and coho salmon, brown trout and rainbow trout were introduced in the late 1960s to reduce the burgeoning alewife population and create an enhanced sport fishery. Significant progress has been made in the rehabilitation of fish communities in Lake Michigan in the last 30-35 years. Reduced sea lamprey numbers, as a result of annual chemical treatments in spawning streams, has reduced lampreyinduced mortality to the point that efforts to reestablish stocks of Iake trout could proceed . The intensive hatchery program that developed to stock Pacific salmon and other stream trout created a trout and salmon sport fishery second to none . Increased salmonine predation on alewives, coupled with environmental variation, substantially reduced the alewife population to the point where indigenous fish species had an opportunity to rebound . In the 1980s, bloater rebounded to abundance levels that exceeded those of alewives at their earlier peak; and yellow perch rebounded to levels that produced near record total harvest . Lack of sustained natural reproduction of lake trout and recent declines in chinook and coho stocks, continue to highlight the need for further rehabilitation of Lake Michigan. Single species management, the focus of rehabilitation efforts thus far, will have to evolve to managing the fish community as a whole following guidelines now being developed for ecosystem management. Fishery agencies who cooperatively manage Lake Michigan, have recently developed draft Fish Community Goals and Objectives to guide fisheries rehabilitation. Though it focuses on the fisheries portion of the Lake Michigan ecosystem, it recognizes that the Great Lakes Water Quality Agreement also needs to be pursued aggressively. Community analyses need to be applied to all trophic levels to meet future information needs .

xlf

Lake Superior findings Lake Superior is the least altered of the Great Lakes, yet the lake, its fishery and its watershed have been significantly degraded . Lake herring, which made up the bulk of the historical commercial catch, have begun to recover following severe depletion . Lake trout, the most economically valuable species in the historical catch, have largely recovered offshore . The status of inshore lake trout stocks is mixed . Some have largely recovered due to stocking and sea lamprey control . Recovery of others is in early stages, or has been slowed by fishery harvest . Some nearshore fishes, especially lake sturgeon and coaster brook trout, are far below historical levels due to overfishing, habitat changes, and effects of introduced species . Two tributary fishes are extirpated from the watershed, and one deepwater species is a candidate for threatened status. Aquatic habitat is generally of good quality, though toxic contaminants are widespread at low levels in the water and sediments . Tributary streams are important for the spawning of some fishes, but some streams are significantly degraded by activities in the watershed, including logging, agriculture, mining and hydropower dams . Nonindigenous species have had perhaps the greatest irreversible effect on Lake Superior : sea lamprey continue to kill thousands of lake trout, rainbow smelt have largely replaced indigenous species as inshore forage, and ruffe threaten the nearshore coolwater fish community . Nevertheless, the agencies that cooperatively manage Lake Superior have made much progress in the past 25-35 years . They have described their vision for the future in the Fish Community Goals and Objectives for Lake Superior, and have reported their progress in achieving that vision in "State of the Lake" reports.

Alpena Fishery Resources Office photo

Recommendations Recommendations

The following recommendations, except where specifically indicated, address issues common to all five of the Great Lakes and their watersheds . These recommendations (see Appendix I for a tabular representation of these recommendations including title and period) identify priorities not currently funded through any of the agencies, but considered essential to meet the Fish Community Goals and Objectives for each of the Great Lakes . Funding necessary to accomplish some of these tasks would be provided to the partners on an equal cost-share basis by the Service, as funds become available . Funding of projects would be accomplished based upon priorities established via a multi-agency committee project approval process to be developed by the Service, the Great Lakes Fishery Commission, and the State and Native American Tribal partners and other interested parties. All recommendations included in this report assume the effective establishment of the aforementioned project approval process, are not limited to funding through or implementation by the Service, and rely heavily on input, funding, and future cooperation among Great Lakes Basin partners . It is expected that future projects addressing these recommendations will focus first on implementation where information is sufficient and on data collection where information is lacking . The Service and Great Lakes Basin partners will work with Congress to further develop these recommendations, some of which could be carried out within existing resources.

Develop and Adopt Aquatic Community and Habitat Goals and Objectives to Support Ecosystem Management Create a mechanism to promote strategic planning, monitoring, and coordination of management activity on a lakeby-lake basis . This will require reconsideration of the central role of objective setting . Various agreements mandate the development of Ecosystem Objectives, Fish Community Goals and Objectives, and Environmental Objectives for the Great Lakes . Ambiguities associated with these objectives, however, have made derivation of indicators and end points nearly impossible and forced managers to make policy choices . Ideally, objective setting represents social preference for trade-offs of user interests as balanced by responsible stewardship for the natural resources of the Great Lakes . A more strategic approach requires : 1) viewing the development of ecosystem objectives as a progressive, vision clarifying process ; 2) developing end points from objectives; and 3) including explicit milestones to gauge progress toward the objectives as part of the objective setting process . In cooperation with the International Joint Commission, Great Lakes Commission, Great Lakes Fishery Commission, other interjurisdictional agencies, the States' resource agencies and Native American Tribal partners, Aquatic Community and Habitat Goals and Objectives should be developed and adopted.

Fully Implement the Strategic Plan for Management of Great Lakes Fisheries The Great Lakes Fishery Convention and the Strategic Plan for Management of Great Lakes Fisheries provide institutional frameworks for coordination of fishery management on the Great Lakes, and linkages to environmental management of the Great Lakes . However, the parties signatory to these agreements need to increase their commitment to implementing these frameworks if the agreements are to be successful . In addition, the Great Lakes Fishery Commission and U .S . and Canadian Federal Governments should quickly propose and provide arbitration procedures acceptable to all signatories of the plan including an evaluation process . If funded at authorized levels, the Act could support the efforts of the signatory parties .

xiv

Recommendatlons :.

Conduct Comprehensive and Standardized Ecological Monitoring Lack of sufficient ecological information exists to make well advised decisions . Limited ecological monitoring at different trophic levels is occurring, however, this needs to be broadened among States, Provinces and agencies, and in time and space . Using improved methods and techniques that are currently being developed, monitor all offshore, nearshore and tributary areas and trophic levels of the ecosystem . Efforts should include density and diversity measurements of the aquatic community, especially phytoplankton, zooplankton, and benthic organisms.

Standardize Fish Community Assessment Data and Establish Comprehensive Fishery Databases Compatibility of assessment data between management agencies is required to meet future needs of the Great Lakes fish community . Usefulness of collected assessment data could be enhanced by establishing database systems that enable maintenance of data integrity among all agencies . The Service should work with other Federal and non-Federal agencies, as appropriate, to develop a uniform, comprehensive lake-wide database containing all available information on : commercial and recreational catch in U .S. waters ; fish stocking ; stock assessment ; coded-wire tagging ; and markrecapture statistics . These databases should be updated on a timely basis in concert with the Lake Technical Committees and individual jurisdictions to achieve data quality and uniformity, as well as continuity with historic data. Programs that will benefit from data standardization include lake-wide creel census programs, lake-wide assessment surveys, stocking programs and recovery of externally and internally marked fish including those with binary codedwire tags. Protocols for data collection, storage and analyses will be developed along with a database management system that will make information accessible to all agencies.

Develop Offshore Capabilities One or more capable offshore research vessels should be deployed on Lake Superior to gather information on offshore and pelagic fish stocks . Construction of the vessel already funded by the U .S. Congress should be completed without further delay . Midwater trawling and hydroacoustics should be incorporated with bottom trawling to better estimate total species biomass and distribution in all areas of the lake.

Fish Community Assessment Program The need to move to fish community management will require fish community research and monitoring . Many current monitoring programs target a single species, often in limited areas . New methods of sampling need to be developed to assess fish communities and their use of available habitat . Understanding fish recruitment mechanisms and the interaction between species before recruitment, will enable managers to develop strategies that will promote self-sustaining fish populations . Ongoing assessment of forage species with hydro acoustic and trawling gear needs to be expanded to include assessments of predator and inshore species . Due to limited vessels to conduct lake-wide assessments, the testing and development of new techniques would require a multi-agency effort . Incorporating existing monitoring programs, such as those using binary coded-wire tags, into a lake-wide fish community assessment also needs to be evaluated . Development and testing of new sampling gear and subsequent protocols will likely take a minimum of five years, after which a specific annual assessment program could be initiated .

Recommendations

Fish Community Modelling Population models combining ecological theory and population dynamics information from assessment programs are useful tools for testing our knowledge of Great Lakes fish community functions and predicting responses to management actions . Recent modelling exercises such as SIMPLE (Sustainability of Intensively Managed Populations in Lake Ecosystems) and IMSL (Integrated Management of Sea Lamprey) have provided valuable insight on species interactions in Lake Michigan, but these models need to be adapted for use in the other Lakes . Further development of population modelling coupled with an enhanced lake-wide assessment program will provide a powerful and necessary tool for the rehabilitation and management of Great Lakes fisheries.

Coordinate State and Native American Tribal Harvest Monitoring and Management : Measure Commercial and Recreational Fish Catches The Service should assist State and Native American Tribal governments in coordination of harvest monitoring and management to ensure that the fishery resource is protected, consistent with the sovereignty and rights of the respective governments . Standardized commercial catch and effort databases need to be developed and historical catch and effort data needs to be integrated with these standardized databases . In addition, fishery agencies should fund and conduct a basin-wide survey to estimate commercial catch and effort, and repeat the survey annually . Currently some agencies conduct recreational fishery surveys while others lack resources to do so . Standard basin-wide creel surveys provide biological, social and economic information for planning and evaluating management actions . A basin-wide creel survey should be conducted to estimate recreational angler catch and effort, the survey should be repeated at intervals sufficient to detect trends in the recreational fishery . The Service should work with the States and Canadian agencies to promote complete creel survey coverage of a uniform quality throughout the Great Lakes.

Evaluate Ecological Effects of Stocking and Revise Stocking Strategies, as Necessary, to be Consistent with Proposed Aquatic Community and Habitat Goals and Ob-

jectives Stocking is used throughout the Great Lakes, however the effects of stocking large numbers of fish on the ecosystem and its ability to sustain those fish is not clearly understood . One technique contributing to the evaluation of the ecological effect of stocking is marking all stocked fish . Marking provides an indirect means of measuring natural reproduction by comparing the contribution of marked and unmarked fish in the fisheries, and a means of evaluating the effectiveness of stocking programs . Where stocking is deemed necessary for restoration or to support local fisheries, stocked fish should be distinctively marked to distinguish them from wild fish of the same species.

Ecological Information Clearinghouse/Geographic Information System To evaluate net loss or gain of fish and wildlife habitat, establish a uniform, comprehensive basin-wide ecological database containing all available information linked to physical location in the each of the Great Lakes . In consultation with the International Joint Commission, Great Lakes Commission, Great Lakes Fishery Commission, other interjurisdictional agencies, the States' resource agencies and Native American Tribal partners, provide, for each Lake, a single clearinghouse for compiled ecological information to meet research and management needs . It is envisioned that this effort would consist of a distributed network, with each agency maintaining its own data in-house and shipping updated files to the ecological information clearinghouse as necessary in read-only format (this process could be made automatic and transparent) . For each of the Great Lakes, a comprehensive Geographic Information System

xvi

Recommendations `'

would house the ecological information . Several initiatives have made progress in the development of Geographic Information System databases, but more effort is required . This effort would focus on determining lake-wide Geographic Information System needs for each Lake and consolidating/interfacing existing Geographic Information System efforts to ensure comparability.

Identify, Inventory, Protect and Rehabilitate Significant Habitats Significant habitats necessary for self-sustaining populations of fish and wildlife are threatened or impaired . Actions should include : identifying and protecting habitats used by fish and wildlife for spawning, breeding, nesting, rearing and feeding ; and rehabilitating degraded habitats to be utilized by a diverse community . Service Coastal Refuges present an opportunity to contribute significantly to this effort.

Develop and Implement Action, Restoration and/or Enhancement Plans for Exploited, and/or Declining Indigenous Aquatic Species Action, restoration and/or enhancement plans are important tools for maintaining integrity and biodiversity of the ecosystem . The Service should support appropriate Lake Committees and stakeholders in the development of action, restoration and/or enhancement plans for declining indigenous species (including unionid mussels, American eel, Atlantic salmon, lake trout, brook trout, coaster brook trout, shortjaw cisco, lake whitefish, walleye, yellow perch, arctic grayling, lake sturgeon, northern pike, muskellunge, smallmouth bass, largemouth bass, common loon, mink and river otter) and exploited species (including steelhead, chinook and coho salmon) . These plans should be developed to be consistent with the proposed Aquatic Community and Habitat Goals and Objectives . Strategies might include, but not be limited to : continuing and expanding monitoring of populations and/or harvest ; standardizing assessment procedures ; setting harvest limits to protect exploited populations ; and identifying and protecting sensitive habitats .

Develop and Implement Action/Restoration Plans for Forage Fish Action plans are an important tool for maintaining integrity and biodiversity of the ecosystem . The Service should support appropriate Lake Committees and stakeholders in the development of an action plan for forage fish consistent with the proposed Aquatic Community and Habitat Goals and Objectives.

"Close the Door" on Nonindigenous Species Introductions Public agencies and non-governmental organizations must cooperate to prevent transport and release of viable organisms into the Great Lakes . Pathways of introduction include ballast water transport, bait bucket transfer, releases from aquaculture or stocking practices and boating. Solutions must be biologically effective, as well as practical, and be based on engineering, operational, regulatory, economic and safety factors . For example, research and development is needed on potential ballast water management options that have already been identified in collaboration with the maritime industry . The studies must be inter-disciplinary, involving biologists and engineers, business operators and government personnel . To support research and monitoring of management options, it will be necessary to develop techniques for bio-sampling of ballast tanks on Great Lakes and ocean-going ships .

Recommendation

Implement and Expand Effective Sea Lamprey Control The U .S . State Department and Fisheries and Oceans Canada, parties to the Great Lakes Fisheries Convention, should meet obligations according to agreed upon funding formulas and fund the Great Lakes Fishery Commission's mandated program . In its Strategic Vision for the Decade of the 1990s, the Great Lakes Fishery Commission has pledged to support fishery management goals by providing an integrated sea lamprey management program that supports the Fish Community Objectives for each of the Great Lakes and that is ecologically and economically sound and socially acceptable" . Fundamental to meeting the vision is an accelerated research program to develop alternative controls to reduce dependence on chemicals, implementation of a control program on the St Mary's River, evaluation of the sterile male release program, and an increase in assessment activities to meet program objectives.

Great Lakes Fishery Commission Line Item Funding for Sea Lamprey Control Efforts in the St . Mary's River The sea lamprey population in the St . Mary's River has been identified as the most serious impediment to sea lamprey control in the Great Lakes . It is also considered one of, if not the most significant, impediments to restoring a healthy fish community in Lake Huron . The size of the river precludes conventional treatment methods and requires the development of specific control strategies . Funding for sea lamprey control has been marginal, at best, over the last several years and has allowed only routine treatments of major lamprey producing tributaries in the upper Great Lakes, excluding the St . Mary's . To ensure proper attention to the most serious problem area, additional funding specifically identified for the St . Mary's River is needed.

Fund Implementation of the Great Lakes Fishery Commission's Basin-wide Sea Lamprey Barrier Plan Construction of low-head dams and electrical barriers to block migrations of spawning adults can reduce lampricide use and provide more effective control by limiting habitat available to lamprey and removing spawning adults at traps. Of the U.S . Great Lakes tributaries regularly treated with lampricide, many have sites where barriers could be constructed. These U .S . projects have the potential to reduce basin-wide lampricide use, cut treated stream mileage, and significantly reduce populations of parasitic lampreys.

Prevent or Delay the Spread of Ruffe The Ruffe Control Program, the first such program to be prepared under the Nonindigenous Aquatic Nuisance Prevention and Control Act, should be implemented by appropriate government and private entities . The program is an integrated plan that addresses each of the ways by which ruffe may spread . Range reduction by chemical treatments, prevention of ballast water transport and education to prevent movement via anglers and bait dealers are all essential to containing the ruffe and must be supported by vigilant monitoring and surveillance . Portions of a control program have been implemented .

Recommendations

Determine the Impacts of Hydroelectric Facilities and Dam Operations on Fishery Resources Fishery resources are impacted by dams inhibiting upstream and downstream passage, creating unstable habitat and causing entrainment-related mortalities . The extent of these impacts on the aquatic community is unknown . Specifically, the following impacts need to be determined : dewatered areas and minimum flow requirements ; water-level fluctuations on fish spawning, fecundity and condition, aquatic vegetation and invertebrates ; and entrainment on fish communities.

20 ,' Increase Involvement in the Binational Program to Restore and Protect Lake Superior and Expand this Mechanism to Lakes Huron, Erie, and Ontario Fishery managers should increase their involvement with the Binational Program.

Establish Uniform Tissue and Sediment Contaminant Levels Used by Various Agencies for Ecosystem Health Contaminant levels for tissue and sediment are inconsistent or absent among agencies . Uniform levels are needed to prevent reproductive, aesthetic, and consumptive impairments . Specific strategies should include evaluation of agency programs that established the current contaminant levels and conducting additional studies to address information gaps .

Broaden the Scope of Current State Antidegradation Policies, Regulations, and Strategies Current State water quality antidegradation policies, regulations, and strategies do not specifically address biological integrity . These policies should be reviewed and revised, if necessary, to clearly state their goal of biological integrity as the Clean Water Act and Great Lakes Water Quality Agreement intend.

Develop and Implement an Action Plan to Analyze Contaminant Level Effects on Aquatic Resources Monitoring of contaminants and analysis of their effects occurs on a limited basis throughout the basin . A plan should be developed to include the following : establishment of regular monitoring at standard locations ; identification of effects on fish reproduction, egg development, fry emergence and larval survival ; identification of effects on plants, plankton, macroinvertebrates and piscivorous wildlife ; and determination of rates of bioaccumulation within the food web.

Participate in Remedial Action Plans, Lake-wide Management Plans, and the Environmental Monitoring and Assessment Program As remedial action projects are implemented, their effects on the fish and wildlife community need to be assessed. Fishery managers should increase their involvement with Remedial Action Plans and contribute to the Monitoring and Assessment Program planning process in the Great Lakes .

xix

Recommendations

Salrnonine Egg Viability The viability of lake trout eggs and Pacific salmon eggs from Lake Michigan, has been a point of concern . Cause and effect relationships need to be explored through research efforts . In addition, the effect of poor egg survival needs to be monitored from a rehabilitation and management perspective, to determine the overall effect on Lake Michigan fish communities. The viability and hatching success of lake trout or salmon that mature in Lake Michigan will provide an indicator of the health of the Lake Michigan ecosystem . A monitoring program needs to be designed to provide a systematic measure of the egg viability of key fish species in Lake Michigan.

Establish an Isolation or Quarantine Facility Management agencies are concerned about maintaining wild genetic traits in hatchery broodstocks of lake trout and possible coaster brook trout . To accomplish this, wild gametes must pass disease clearance in an isolation facility prior to introduction to hatchery systems . Such a facility should also be designed to support imported adult salmon and other fish from outside the Great Lakes Basin for broodstock development and should be capable of isolating six lots of fish.

Develop an Epizootic Epitheliotrophic Disease (EEDV) Diagnostic Test A diagnostic test for EEVD is needed to expedite determination of disease in lake trout eggs and young fish for the purpose of establishing lake trout broodstocks from wild Great Lakes stocks.

Fish Health Low egg viability and diseased salmonids are examples of the problems that develop when recruitment of these predators is dependent on intensive aquaculture . Maintenance of fish health within the hatchery has been well researched. Wild fish health and its potential to be an indicator of ecosystem health is a field of study that is not as well developed. Appropriate indicators of fish health should be developed for key fish species in the wild . An example is the recent decline of chinook salmon in Lake Michigan where a lack of knowledge concerning fish health in the wild exists.

Fish Genetics Since the collapse of indigenous Great Lakes fish and fisheries in recent decades, the rehabilitation of indigenous fishes is an attempt to recolonize the Lakes, a phenomenon that occurred historically following periods of glaciation . The extinction of gene pools adapted to the Lakes for species like lake trout and possibly lake herring, raises concern over the ability of available genetic strains to effectively recolonize all of the available habitat . Analyses of available genetic strains and their survival in the Lakes are crucial for indigenous species restoration efforts.

Lethality of Sea Lamprey Attacks Research is needed to evaluate the effects of sea lamprey wounding on mortality of fish species other than lake trout. For example, attacks on chinook salmon are extensive, but the timing of these attacks and their contribution to

Recommendations

overall mortality is not known . Research has been conducted with lake trout to quantify mortality resulting from sea lamprey attacks but similar work is needed with other species, especially in light of burgeoning lamprey populations in northern Lake Huron.

Develop Aquatic Resource Education Programs Education programs focusing on the values, functions and dynamics of ecosystems are needed so that society understands their role in the system and makes informed decisions . Education programs should focus on issues such as the prevention and control of nonindigenous nuisance species introductions, the role of deliberately introduced nonindigenous self-sustaining and supplementally-stocked species, indigenous species restoration (e .g. lake trout, lake sturgeon), habitat restoration, and endangered species.

Conduct a Cormorant Fishery Predation Study A fishery predation study to determine the diet of the Great Lakes cormorant population, similar to that started in 1992 by the Fish and Wildlife Service, Canadian Wildlife Service and New York State Department of Environmental Conservation should be conducted for each of the Great Lakes to quantify fishery predation and generate recommendations to decrease predatory impacts on newly-stocked fish, if necessary.

Courtesy of Environmental Research Institute of Michigan, Ann Arbor, MI

I

introduction

Purpose of the Document In response to the Congressional request for information on the Great Lakes and progress in implementing the Great Lakes Fishery Resources Restoration Study(Study)required in the Great Lakes Fish and Wildlife Restoration Act (1990) 16 U.S.C.@ 941 et seq., this report herewith provides results obtained. Due to the limited appropriation of funds the Study was, by necessity, limited in focus . However, progress was made on all five major Study components throughout the Great Lakes Basin.

Great Lakes Fish and Wildlife Restoration Act Historic perspective "For thousands of years, indigenous populations have been relying, to some extent, on the Great Lakes for their livelihood . . ..These waters provided an abundant fishery for the peoples of the emerging peninsula, and the large lakes were viewed with wonder and awe . Cultures rose and were supplanted by other indigenous cultures . Eventually, the Anishnabeg (Ojibway, Ottawa, and Potawatomi) took possession of the land after a series of migrations which originated on the Eastern Seaboard . They moved from one aquatic environment to another and possessed the technology to effectively harvest large numbers of fish from the waters of Mi-chi-gum, Mi-chi-ganing, or Mi-chi-go-nong, as the lakes were called . The name translated to "big or large lake/water" and was used to collectively refer to the very large bodies of water that surrounded the region's peninsulas . .. .an important part of a tradition and legacy that has been bestowed on the region by Native peoples. ...In the post Civil War period, . . .the Great Lakes fishery was "harvested" with a vengeance. Na-me, the Sturgeon, an important fish to the Anishnabeg, became a rarity as a result of targeted commercial fishing . The large Sturgeons wreaked havoc with commercial nets and therefore were marked for extermination . The average size of Lake Trout declined precipitously . Fifty and sixty pound fish became rarer and rarer and the end was not in sight . On land, the same things were happening . The enormous White Pine forests were being cut at an astronomical rate while market hunting was taking an enormous toll on wildlife . Unfortunately these trends continued into the 20th century and in many instances were responsible for irreparable harm to the fishery, flora and fauna . . . ." (Cornell 1993). Background information The Great Lakes provide an immense natural resource for the people of the United States and Canada . The five Great Lakes contain 20 percent of the world's fresh surface water and cover approximately 246,049 square kilometers (95,000 square miles) . Approximately 25 percent of the total population of Canada and 10 percent of the U.S. population live within the Great Lakes Basin and about 25 million people use it as a water supply . The water-related resources are an integral part of activities such as outdoor recreation and tourism valued at $15 billion annually, $6 .89 billion of which is related to the fishing industry . Additionally, the Great Lakes Basin contains over 728 square kilometers (281 square miles) of coastal wetlands which provide habitat for endangered species and breeding areas for waterfowl, other migratory birds, and fish. The demand for harvestable fishery resources offers an increasingly difficult challenge . Historically, large numbers of lake trout, lake whitefish, lake herring, walleye, blue pike, lake sturgeon, yellow perch and other fish populated the Great Lakes and supported a major commercial fishing industry . In Lake Ontario, Atlantic salmon were gone by 1900 and sturgeon were severely depleted . Populations of commercially valuable fish further declined precipitously during the 1950s and 1960s due to a combination of factors, including over-fishing, sea lamprey predation, competition with nonindigenous nuisance species, and pollution . Resource management agencies throughout the Great Lakes region responded by implementing aggressive long-term programs designed to restore the fisheries, including the introduction of nonindigenous hatchery-reared salmon, lake trout stocking and sea lamprey control.

2

Introd uctlOils:

To varying degrees these programs have succeeded and the Great Lakes are once again vital to the recreation and economy of the region . Participants in the fishing industry in the U .S. generate about $2 .22 billion in sales to local businesses and the industry represents $4 .4 billion in annual economic activity . About 75,000 jobs are supported by sport fisheries, and commercial fisheries provide an additional 9,000 jobs and $270 million annually . A small portion of the commercial harvest is taken by tribal fisheries that operate pursuant to treaties dating from 1836 and 1842. These public values and benefits are confirmed by an extensive body of Federal legislation and international treaty conventions that pertain to the Great Lakes . The U.S . Fish and Wildlife Service (Service) has been granted a number of these authorities (see Appendix III) . The roles and responsibilities of the Service for Great Lakes resources pertain primarily to protection of anadromous, migratory, endangered, inter-jurisdictional (or international) species and management of federal lands. Nonindigenous nuisance species such as the sea lamprey, zebra mussel, ruffe, spiny water flea, purple loosestrife, and Phragmites continue to threaten the indigenous living resources in the Great Lakes . In addition to the threats that nonindigenous nuisance species impose, water level regulations, channelization, hydropower dams, shoreline structures, and filled wetlands challenge Indigenous species at various stages in their life cycles. The living resources in the Great Lakes must be carefully managed to ensure maximum public benefit while guaranteeing their perpetuation . The goals and objectives of the international cooperative efforts between the United States and Canada will be realized as the health of fish and wildlife resources improves. Restoration goals for the Great Lakes Basin will be met when viable and productive stocks of indigenous and other desired fish species are available, bald eagles successfully reproduce and inhabit shorelines, mink and otter re-inhabit suitable shorelines throughout the Basin, chemical and other stress-induced deformities in fish and wildlife are reduced or eliminated and fish and wildlife can be consumed with little or no risk to human health. The complexity of the Great Lakes ecosystem is matched by the complexity of the institutional framework in place for Great Lakes management . The Great Lakes system is managed at many levels from municipalities to national governments : two Federal governments, eight States, Native American Tribes, and two Provinces share responsibility in the system along with municipalities, county boards, and regional and international bodies such as the Great Lakes Fishery Commission, Great Lakes Commission and International Joint Commission . Adding to this management complexity is the diversity of interests represented by research institutes, universities, citizen groups, businesses, and private individuals within the Great Lakes Basin. Adoption of an ecosystem perspective in the stewardship and rehabilitation of Great Lakes resources is widely recognized as crucial for the future of the system . Current resource assessments, and research and management tools alone are inadequate to evaluate changes in large complex ecosystems . New tools must be developed as an outgrowth of partnership efforts to identify ecosystem Impairments, focus rehabilitation efforts, adaptively manage resources and monitor results. The Service has the capability to act as a catalyst in the development of an ecosystem based approach to resource conservation in the Great Lakes . The size and complexity of the Great Lakes and the objectives of the Great Lakes Fish and Wildlife Restoration Act (Appendix IV) require partnerships to guarantee success in resource conservation. The Service's approach to insure that cooperation and partnerships flourish in Great Lakes activities is simple : 1) coordinate internally and externally with all identified partners constantly, and 2) remind ourselves on a daily basis that in some Great Lakes activities, the Service will provide leadership ; in others, the Service may aid or simply provide the technical assistance, as requested, to our partners, necessary to achieve shared goals. Based upon the progress being made by Great Lakes ecosystem partners, the future outlook for rehabilitation is bright. Purposes of the Act

The Act (Appendix IV) directs the Service : to provide technical assistance to the Great Lakes Fishery Commission, States, Native American Tribes and other interested entities to encourage cooperative conservation, restoration and management of the fish and wildlife resources and their habitats in the Great Lakes Basin; to carry out a comprehensive study of the status, and the assessment, management and restoration needs, of the fishery resources of the Great Lakes Basin; and to develop proposals to implement recommendations resulting from that study .

3

Introduction

The Act also provided for the establishment of offices . A centrally located Great Lakes Coordination Office was established in East Lansing, Michigan for intra- and interagency coordination, information distribution and to promote public awareness of all Service activities in the Great Lakes Basin . The Lower Great Lakes Fishery Resources Office was established in Amherst, New York, to carry out all Service operational activities related to fishery resource protection, restoration, maintenance and enhancement in the Lower Great Lakes . Additionally, the Ashland, Wisconsin Fishery Resources Office was expanded and Fisheries Resources Offices were established in Green Bay, Wisconsin and Alpena, Michigan to perform similar activities in the Upper Great Lakes.

Great Lakes Fishery Resources Restoration Study The Act requires the Director of the Service to conduct a study of the status of the fishery resources of the Great Lakes Basin, hereafter called the Study, in collaboration with State and Native American Tribal partners and the Great Lakes Fishery Commission . The Study is to focus on the assessment, management, and restoration needs of Great Lakes fishery resources. The Service invited State and Native American Tribal entities to enter into a memorandum of understanding regarding the Study (Appendix V) and coordination of Great Lakes activities. During fiscal years 1992, 1993, and 1994, the Service met with all of the States and Native American Tribes bordering the Great Lakes to develop a better understanding of unmet fishery resource needs . The meetings also provided an opportunity to discuss the Service's role within the Great Lakes Basin . Cooperative projects and planning between the States, Native American Tribes and other partners are currently underway . The Fishery Resources Offices are assisting Lake Committees of the Great Lakes Fishery Commission with implementation of the 1980 joint Strategic Plan for Management of Great Lakes Fishery Resources (hereinafter referred to as Strategic Plan for Management of Great Lakes Fisheries Study Objectives The Act outlined five Study objectives to be addressed by the Service and its partners. Study Objective I:

Identify and describe the component drainages of the Great Lakes Basin by including the drainage for each of the Great Lakes and analyzing how the characteristics and current or expected land and water uses of those drainages have affected, and can be expected to affect in the future, the fishery resources and fish habitats of the Great Lakes Basin. Study Objective II:

Analyze historical fishery resource data for the Great Lakes Basin to identify the causes of past and continuing declines of the fishery resources and the impediments to restoring those resources. Study Objective III:

Evaluate the adequacy, effectiveness, and consistency of current Great Lakes interagency fisheries management plans and Federal and State water quality programs, with respect to their effects on Great Lakes fishery resources. Study Objective IV:

Analyze the impacts of, and management control alternatives for, recently introduced nonindigenous species, including the zebra mussel, the ruffe, and the spiny water flea in accordance with the Aquatic Nuisance Prevention and Control Act of 1990. Study Objective V:

Develop recommendations and action plans including: "(A)

an action plan to analyze the effects of contaminant levels on fishery resources;

"(B)

an action plan for the cooperative restoration and enhancement of depleted, nationally significant fish



4

Introduction

stocks, including lake trout, yellow perch, lake sturgeon, walleye, forage fish and Atlantic salmon; "(C)

planning and technical assistance that should be provided to the Great Lakes Fisheries Commission, States and Indian Tribes to assist their fishery resource restoration efforts;

"(D)

mitigation measures to restore and enhance fishery resources adversely affected by past Federal (including federally assisted or approved) water resource development projects and other activities;

"(E)

increasing the involvement of the International Joint Como ; ission, the Great Lakes Commission, the Great Lakes Fishery Commission, and other interjurisdictional entities regarding fishery resources protection, restoration and enhancement;

"(F)

research projects and data gathering initiatives regarding population trends of fish stocks, including population abundance arm structure, interspecific competition, survival rates and behavioral patterns;

"(G)

identifying important fishery resource habitat and other areas that should be protected, restored, or enhanced for the benefit of Great Lakes fishery resources;

"(H)

identifying how private conservation organizations, recreational and commercial fishing interests, the aquaculture industry, and the general public could contribute to the implementation of the fishery resource restoration and enhancement recommendations developed pursuant to this Act ; and

"(I)

identifying appropriate contributions that should be made by States and other non-Federal entities to the cost of activities undertaken to implement the recommendations, including a description of "( i)

the activities that shall be cost-shared;

"(ii)

the entities or individuals which shall share the costs of those activities;

"(iii)

the proportion of appropriate project and activity costs that shall be borne by non-Federal interests ; and

"(iv)

how the entities or individuals who share costs should finance their contribution.

Limited progress has been made on all five of the Study objectives throughout the Great Lakes . Based upon availability of information from work initiated prior to the Act and ongoing work related to the Study, Lakes Ontario and Erie were addressed using a trophic guild approach . Lakes Huron, Michigan and Superior were addressed using a habitat-based fish community approach. Development of proposals The Service, in collaboration with partners participating in forums such as the Lake Committee structure of the Great Lakes Fishery Commission and the Service's Great Lakes Basin Ecosystem Team, will aid in the development of proposals to implement the recommendations of the Study . Some of these proposals are contained in this report, but most will be developed subsequent to further work . Based upon available funding, proposals will be prioritized via a multi-agency committee project approval process developed by the Service, the Great Lakes Fishery Commission, and the State and Native American Tribal partners . The proposals will use an ecosystem approach to incorporate the goals of the Great Lakes Water Quality Agreement, as revised in 1987, the 1954 Great Lakes Fisheries Convention, State and Native American Tribal natural resource management agencies, and the Strategic Plan for the Management of Great Lakes Fisheries .



5

y'

lair

- .,~ .'

y?

ntroductton p

Great Lakes Basin Description Great Lakes climate The Great Lakes (Figure 2) are located in the northern temperate zone and have been characterized as having a humid microthermal climate consisting of rain and snow with cold winters . The Great Lakes climate is modified by the lakes themselves, resulting in a partial maritime with southwesterly winds in the summer and southeasterly winds in the winter (Berst and Spangler 1973; Ryder 1972) . Figure 2 . Map illustrating the Great Lakes watershed (U .S. Environmental Protection Agency and Environment Canada 1988).

Physiographics, hydrographics, and trophic state The Great Lakes-St . Lawrence system contains the St . Lawrence and St. Mary's Rivers and Lakes Ontario, Erie, Huron, Michigan, and Superior and connecting channels . Each of the five Great Lakes is among the fifteen largest freshwater lakes in the world and the system contains 65 trillion gallons of fresh water ; a full 20 percent of the world's supply and 90 percent of the U .S. supply (Donahue 1991) . A discussion of physiographics, hydrographics, and trophic state of each of the Great Lakes follows.

Lake Onta Physiographics and hydrographics Lake Ontario (Figure 2) is the smallest of the Laurentian Great Lakes in surface area, but it is the twelfth largest lake in the world by volume (Table 1). Lake Ontario is divided into four Figure 3 . Map illustrating the four basins of Lake Ontario . basins (Figure 3) . The three major basins - the Niagara, Mississauga, and Rochester basins, from west to east, are separated by the Whitby-Olcott and Scotch Bonnet sills, respectively . The eastern most, Kingston basin, is separated from the Rochester basin by the Duck-Galoo sill. The sediments follow a gradient of sands and gravels in the nearshore areas to silts and clays in the deeper portion of the basins . The Niagara basin has a maximum depth of 128 meters (420 feet), while the Mississauga basin maximum is



6 tl ntrod Uctioh i:

Table 1 . Great Lakes physiographic and hydrographic features.

Length

kilometers

miles kilometers miles meters feet meters

Breadth Elevation Maximum depth

feet

Mean depth

meters feet

cu.km. cu.mi . cu.m./sec. cu.ft./sec.

Volume Discharge Retention time

years

Area: Water Land drainage area

a

Total Shoreline Length

b

sq.km. sq.mi sq .km. sq .mi. sq .km. sq .mi. kilometers miles

Ontario 311 193 85 53 75 246 244 801 84 276 1,640 393 6,877 243,000 6 .0

Erie 338 210 92 57 174 571 64 210 19 62 484 116 5,730 202,269 2 .5

Huron 330 205 293 182 177 581 229 751 55 180 3,540 850 5,297 186,970 23 .0

Michigan 494 307 190 118 177 581 281 923 85 279 4,920 1,180 1,588 55,000 99 .0

Superior 563 350 257 160 183 601 406 1,333 148 487 12,200 2,927 2,126 75,051 182 .0

Total 2,081 1,293 nla nla nla nla n/a n/a nla nla 22,784 5,466 n/a nla nla

18,960 7,340 64,030 24,720 82,990 32,060 1,146 712

25,700 9,910 78,000 30,140 103,700 40,050 1,402 871

59,600 23,000 134,100 51,700 193,700 74,700 6,157 3,827

57,800 22,300 118,000 45,600 175,800 67,900 2,633 1,638

82,100 31,700 127,700 49,300 209,800 81,000 4,385 2,726

244,160 94,250 521,830 201,460 765,990 295,710 17,017 10,210

c c

a Land drainage area for Lake Huron includes the St . Marys River, Lake Erie includes the St . Clair-Detroit, system and Lake Ontario includes the Niagara River. b Including islands. C

These totals are greater than the sum of the shoreline length for the lakes because they include the connecting channels (excluding the St . Lawrence River) . (adapted from Erdevig, 1991)

about 201 meters (659 feet) . The Rochester basin drops to approximately 245 meters (803 feet) . The Kingston basin has a maximum depth of 30 meters (98 feet), although the average depth is much less . Islands and extensive littoral area are common in the Kingston basin . (Eckert 1984; Martini and Bowlby 1991 ; Sly 1991). Natural shoreline structure is quite variable around the lake, ranging from bluffs of varying composition to low lying sandy beaches. Coastal marshes are commonly found in embayments and creek mouths . In addition to agriculture, extensive urbanization, particularly in the vicinities of Toronto, Hamilton, and Rochester, has significantly impacted the shoreline and associated wetlands (Living with the Lakes 1989) resulting in a loss of 50 percent due to urbanization

7

oductiorv:

of greater than 80 percent of the shoreline in these areas (Whillans et al. 1992) . The Lake Ontario shoreline is more complex in the east (Kingston basin) than it is in the western and central portions . Contributing to the complexity in the eastern section is the Bay of Quinte, which has numerous small embayments and a highly convoluted shoreline. The eastern portion of the Bay is dominated by bedrock outcroppings. Lake Ontario receives all of the outflow from the upper four Great Lakes via the Niagara River, at the average annual rate of 5,520 cubic meters per second (194,856 cubic feet per second) . Direct inflow from all other major tributaries adds an additional 540 cubic meters per second (19,062 cubic feet per second) (Sly 1991) . Theoretical water retention time is about six years because of the great inflow from the Niagara River (Living with the Lakes 1989) . Modern fluctuations in the water level of Lake Ontario are less than 2 meters per year, far less than historical fluctuations (Great Lakes-St . Lawrence River Regulation 1990 ; Sly 1991), largely as a result of artificial water-level regulation coupled with a relatively small surface area, which limits evaporation effects. Lake Ontario stratifies thermally in summer and winter, and mixes in spring and fall . Summer stratification is well pronounced, resulting in classical zonation, while winter stratification is rather weak . Due to its large heat capacity, Lake Ontario usually remains free of ice in the winter, with the exception of inshore shallows and sheltered embayments . Hypolimnetic upwellings of cold water from the deep are common, even during maximum summer stratification . Vertical thermal bars are a feature of the warming and cooling processes of the lake and serve to temporarily segregate inshore and offshore waters, particularly at the onset of summer stratification . The isolation of inshore waters serves to restrict dispersion of nearshore pollutants, nutrients and other loadings (Eckert 1984) . Circulation is typically wind driven, and frequently characterized by several cells, corresponding generally with the subbasins. Trophic State The trophic status of Lake Ontario has recently been regarded as mesotrophic, based on average phosphorus concentrations (Living with the Lakes 1989; Leach and Herron 1992) although many inshore areas and embayments are decidedly eutrophic . Lake Ontario has had a productive sport fishery that is changing quickly . Very high, artificial levels of nutrients and primary productivity in the open waters are down significantly (Smith and Lange 1994)tending towards oligotrophic. The phytoplankton community of Lake Ontario is dominated by diatoms, green algae, dinoflagellates, and flagellates, which together comprise 90 percent of phytoplankton . Cladophora sp. are the predominant attached alga . The zooplankton community is largely composed of Bosmina longirostris and Daphnia retrocurva (rohannsson and O'Gorman 1991) . The deepwater benthos is populated by Disporia hoyi and Mysis relicta, while the more eutrophic, nearshore regions are characterized by a predominance of oligochaetes, particularly Potamothrix species and Aulodrilus species. The current trophic status is approaching oligotrophic in most of the open water with changes in nutrients impacting primary and secondary productivity.



8

ntroductian%R

Lake; Erie i j Physiographics and hydrographics Lake Erie is the shallowest, most southern, and warmest of the Great Lakes and lies at the boundary of the humid microthermal and humid mesothermal climates . It is the fourth largest of the Laurentian Great Lakes in surface area and the smallest by volume (Table 1). Lake Erie is divided into three basins (Figure 4) . The western and central basins are separated by the PeleeLorraine Sill, and the central and eastern basins are separated by the Long Point-Erie Sill . The western basin is the shallowest, with a maximum depth of 20 meters (67 feet), and an average depth of 7 meters (24 feet) . The Figure 4 . Map illustrating the three basins of Lake Erie. central basin is the largest in surface area (63 percent of the total), and has a maximum depth of 26 meters (84 feet), and an average depth of 19 meters (61 feet) . The eastern basin is the deepest, with a maximum depth of 64 meters (210 feet) and an average depth of 24 meters (80 feet). DEPTH IN METERS

Lake Erie is a typical dimictic lake, undergoing spring and fall mixing . Summer stratification occurs in the central and eastern basins . Most of the lake is covered with ice in the winter. The substrate is a combination of bedrock (composed of marine sedimentary rock including limestone, dolomite, shale, and sandstone), sand and gravel in the nearshore, and mud in deeper areas . The shoreline includes bluffs, sandy beaches, and coastal wetlands . Islands are present in the western basin and along the Pelee-Lorraine Sill . Most of the natural reefs also occur in the western basin. The Lake Erie basin features several types of coastal wetlands, including estuarine wetlands, coastal lagoons, and managed marshes . The highest concentration of coastal wetlands occurs in western Lake Erie . Severe northeast and northwest storms create rapid fluctuations of water levels and waves that erode the shoreline ; these events inhibit the development of coastal wetlands in many other areas. Estuarine wetlands are drowned river mouths, where the major water input is from one or two tributaries . Most of the tributaries along the southwestern shore create estuarine wetlands . The more important estuarine wetlands include : Old Woman Creek Estuarine Sanctuary, the lower Maumee River, the lower Sandusky River and Sandusky Bay, and Big Creek Marsh. Coastal lagoons derive their water from the lake and are separated from it by a sand spit or barrier beach . Coastal lagoons around Lake Erie include Sheldon Marsh, just east of the mouth of Sandusky Bay, and Point Pelee, Ontario. Managed marshes are areas that have been diked and have gates to maintain desired water levels . Examples of these marshes around Lake Erie include Winous Point Marsh and Moxley Marsh in Sandusky Bay, and Ottawa National Wildlife Refuge, Metzger Marsh, and Magee Marsh located between the Maumee and the Portage Rivers. More than 90 percent of the total inflow to Lake Erie comes from the Detroit River . The average annual inflow at the head of the Detroit River is 5,140 cubic meters per second (181,442 cubic feet per second) . Average annual inflow from tributaries and surface runoff is estimated at 580 cubic meters per second (20,474 cubic feet per second) . Water residence time in Lake Erie is a short 2.5 years due to the small volume . Outflow from Lake Erie is through the Niagara River and the Welland Canal . The Combined outflow averages approximately 5,730 cubic meters per second (202,269 cubic feet per second).



9

Introduction

Trophic State Lake Erie historically had the highest productivity of all the Great Lakes, and is still as productive a fishery as the other four Great Lakes combined . The trophic status or productivity of the lake has changed dramatically in this century due to increased nutrient input, especially phosphorous . Nutrient loadings increased dramatically through the 1950s and 1960s, increasing phytoplankton three-fold from 1927 to 1962, and twenty-fold by 1973 . As a result, the trophic status was classified in the 1970s as mesoeutrophic in the eastern and central basins, and eutrophic in the western basin . Phosphorous abatement programs started in the 1970s have reduced the nutrient loading significantly over the last two decades, decreasing productivity to the more oligotrophic historical conditions in the eastern and central basins and mesoeutrophic in the western basin. Lake Huron Physiographics and hydrographics Lake Huron (Figure 2) is the fifth largest lake in the world and the second largest of the Laurentian Great Lakes . It has the longest shoreline and the third largest water volume (Table 1) . Descriptions of lake morphometry have been reviewed by Berst and Spangler (1973), Ristic (1989) and Michigan Sea Grant (1992). Formed approximately 10,000 years ago following the

oC>,„

CONTOURS

E,~RS

Wisconsin glaciation (Ryder 1972), Lake Huron has a r-,=. -.4- - Ifdrainage basin of 193,700 square kilometers (74,000 1 square miles), one-third of which is the lake surface (Berst and Spangler 1973) . The north shore is mainly Figure 4a . Lake Huron contour map . Precambrian in origin while the remainder of the lake bed is Paleozoic (Hough 1958) . A portion of the Niagran Escarpment, a Devonian rock formation, extends from the northern to the southeastern part of the lake and is present as a chain of islands and a peninsula. ~.

.

Lake Huron is comprised of three basins ; the main basin, the North Channel, and Georgian Bay. The main basin is the largest and has a surface area of 41,659 square kilometers (16,085 square miles) and an average depth of 61 meters (200 feet) (Berst and Spangler 1973) . The North Channel is located on the northeastern coast of the lake and is separated from the main lake by a chain of islands . Its surface area is 4,550 square kilometers (1,757 square miles) with an average depth of 22 meters (72 feet) (Berst and Spangler 1973) . Georgian Bay, located on the eastern coast of the lake and defined from the main basin by the Bruce Peninsula, is the largest bay in the Great Lakes system . Its surface area is 13,752 square kilometers (5,310 square miles) with an average depth of 51 meters (167 feet) (Berst and Spangler 1973). There are two major bays, Georgian Bay and Saginaw Bay . Georgian Bay, described above, is a prominent feature and the largest bay in the lake . Saginaw Bay on the western shore of Lake Huron is the second largest bay in the Great Lakes system . It is 42 kilometers (26 miles) wide and projects 82 kilometers (51 miles) into the land mass (Beeton et al . 1967). Its surface area covers 2,960 square kilometers (1,143 square miles) and is divided equally into a shallow inner bay, 5 meters (15 feet) average depth, and a deeper outer bay, of 16 meters (51 feet) average depth (Beeton et al . 1967). Two main subsurface ridges are located in Lake Huron, the Six Fathom Scarp, and the Ipperwash Scarp . The Six Fathom Scarp extends across Lake Huron from Alpena, Michigan to Kincardine, Ontario and divides the lake proper

14

n', FeWORIP't'RIP Introduction

into two distinct basins . Southwest of the ridge the lake is uniform, having a maximum depth of 91 meters (299 feet); and north of the ridge a deep trough exists, having a maximum depth of 229 meters (751 feet) (Berst and Spangler 1973). The deepest waters of Lake Huron and many concentric shoals are located north of this ridge (Berst and Spangler 1973) . The Ipperwash Scarp is located south of the Six Fathom Scarp. There are over 30,000 islands in Lake Huron, the majority in Georgian Bay. A prominent chain of islands in the northern part of the Lake separates the main basin from the North Channel and Georgian Bay . Manitoulin Island, the main island of this chain, is the largest in Lake Huron and the largest freshwater island in the world . Drummond and Cockburn Islands are also part of this chain. Major waters which enter Lake Huron include outflows from Lakes Superior and Michigan, and stream flow from tributaries . With an elevation equivalent to that of Lake Michigan (Table 1), Lake Huron and Lake Michigan form a hydrological unit and continuous water body at the straits of Mackinac (Berst and Spangler 1973) . Lake Huron receives the outflows from Lake Superior of approximately 2,126 cubic meters per second (75,051 cubic feet per second) and from Lake Michigan of approximately 1,558 cubic meters per second (55,000 cubic feet per second), which enter the lake in the north by way of the St. Mary's River and the Straits of Mackinac respectively (Table 1). Major U .S. tributaries enter the lake to the west and include, from north to south : the Cheboygan River, Thunder Bay River, Au Sable River, and the Saginaw River . Major Canadian tributaries enter the lake to the north and east and include, from north to south : the Mississagi River, Spanish River, French River, Magnetawan River, Muskoka River, Severn River, and the Saugeen River . The St . Clair River, at approximately 5,297 cubic meters per second (186,970 cubic feet per second), drains the lake to the south and leads to Lake Erie by way of the Lake St .Clair/ Detroit River system (Bolsenga and Herdendorf 1993) . The residence time of water in Lake Huron is 23 years (Berst and Spangler 1973). Water circulation is anticyclonic and flows from north to south . In the main basin, currents follow the western shore south into Saginaw Bay and along the submersed ridge, circling north again off the coast of the Bruce Peninsula and into Georgian Bay . Currents also flow out of the St . Mary's River, along the northeastern shore through the North Channel into Georgian Bay. A humid continental climate consisting of a cool summer but no dry season is prevalent in the region with an annual average precipitation of 873 millimeters (34 inches) . There is a dimictic thermal regime in the Lake, generally yielding a spring turnover in May and a fall turnover in November (Rockwell et al . 1989) . The component basins and water bodies have different physical, thermal and chemical characteristics (Berst and Spangler 1973) . For example, thermoclines form at different times and depths in the main basin and in Georgian Bay due to differences in their physical and chemical properties. Trophic State Lake Huron waters are oligotrophic, except in eutrophic areas of Saginaw Bay (Berst and Spangler 1973) . Lake nutrient concentrations were low compared to the other Great Lakes due to low loading, and the annual concentration ranges were small (Moll et al. 1987) . The surface waters have low concentrations of chlorophyll a ranging from 0.3 to 1 .3 micrograms per liter (Rockwell et al . 1989) . Oxygen saturation levels were generally in excess of 90 percent (Dolan et al . 1986) and at all depths throughout the year (Berst and Spangler 1973) .

11

p~~introduction

Lake Michigan ; Physiographics and hydrographics Lake Michigan (Figure 5) is the third largest of the Laurentian Great Lakes (Table 1) and the sixth largest lake in the world (Beeton 1984) . It is the only Great Lake wholly within the U .S., bordered by the states of Illinois, Indiana, Michigan, and Wisconsin . However, because of movement of fish between Lake Michigan and Lake Huron and of its discharge to Huron 1,588 cubic meters per second (55,000 cubic feet per second), the lake is important internationally . The Lake Michigan watershed is slightly more than twice the surface area of the lake (Table 1), and is near equally split between the east and west side of the lake . Most of the watershed lies in the upper and lower peninsulas of Michigan and northeastern Wisconsin with very little in Illinois and Indiana. The northern part of the Lake Michigan watershed is covered with forests, sparsely populated and economically dependent on natural resources and tourism . The southern portion of the watershed is heavily populated with intense industrial development and rich agricultural areas along the shore. Elongated in shape, Lake Michigan is divided into a Figure 5 . Lake Michigan contours. southern basin that is relatively smooth in contour, sloping to a maximum depth of 170 meters (558 feet), and an irregularly shaped northern basin with a maximum depth of 281 meters (923 feet) . Wells and McLain (1973) provide an excellent summary of the limnology of Lake Michigan, and the brief description provided here is excerpted from their paper. The world's largest freshwater dunes line the lake shore . Millions of people annually visit the dunes/beaches at State and National parks and lake shores . Major tributaries to Lake Michigan are the Fox-Wolf River system in Wisconsin and the St. Joseph, Grand, Muskegon, Manistee, Pere Marquette, Menominee, and Kalamazoo Rivers in Michigan. There is an out-of-basin diversion through the Illinois Waterway at the Chicago River. Trophic State The waters of Lake Michigan have been enriched with loadings of municipal and industrial waste and agricultural runoff. However, the bottom waters remain well oxygenated and, with the implementation of the 1972 Great Lakes Water Quality Agreement, estimated loadings of phosphorus appear to be low enough to preserve its oligotrophic state (International Joint Commission 1989) . Enrichment is mainly a problem in specific localities such as southern Green Bay where excessive loadings have degraded the sediments. Green Bay, a major embayment connected to the northern basin, is 190 kilometers (118 miles) long, relatively shallow and more productive on a surface-area basis than is Lake Michigan proper . Lake Michigan is classified as oligotrophic with features characteristic of deep, cold lakes . Biological production in oligotrophic lakes is low compared to shallow and nutrient-richer lakes such as Lake Erie . Lake Michigan has been a major producer of valuable fishery products

12

Introduction more because of its great size than its fertility . The lake has also been subjected to a plethora of toxic contaminants, most notably a complex mixture of PCBs. Although Lake Michigan proper has not been severely impacted physicochemically by human settlement of the basin, the alteration of streams by deforestation, damming, draining of swamps and pollution has seriously impaired their usefulness for fish reproduction . Many native species of fish such as lake whitefish spawned in the lake and in streams, but the river-spawning forms are now greatly depleted or extinct (Smith 1972) . Despite these impairments, Lake Michigan remains a magnificent resource, and can produce high sustainable yields of valuable fishery products. Lake .: Superior Physiographics and hydrographics Lake Superior (Figure 6) is one of the world's great inland seas -- the biggest, deepest, coldest and clearest of the five Laurentian Great Lakes (Table 1) ; a habitat so unique that it developed races of fish found nowhere else ; a volume of water so massive, representing more than half of the total volume of all the Great Lakes (Matheson and Munawar 1978), that the seasons only begin to cool or to warm it ; a sea whose depths are little known, because humans frequent only its fringes . Lake Superior lies at the head of the St . Lawrence River . , drainage, its surface 183 meters (600 feet above mean sea +46 30 87. level, but its deepest point is more than 213 meters (700 feet below sea level. Due to the constant isostatic uplift Figure 6 . Lake Superior contours. of the Sault St . Marie outlet for the past 4,000 years, western Lake Superior has experienced a continued rise in mean lake level, upon which has been superimposed both higher and lower lake level episodes related to climate changes (Larsen 1994) . From its location in the middle of the continent, its waters flow 2,081 kilometers (1,293 miles) to the east before mixing with salt water in the Gulf of St . Lawrence . The shoreline is almost evenly divided area lies in the United States. The drainage basin of lake Superior encompasses 127,700 square kilometers (49,300 square miles) . About 39 percent of the total drainage basin is made up of the lake itself (Upper Lakes Reference Group 1976). The lake lies along the southern edge of the Canadian Shield, a region of complex geological history dominated by granite and sandstone overlain by glacial till (Lawrie and Rahrer 1973) . The eastern portion of the north shore is within the Superior Province of the Shield, characterized by irregular tumbled hills, the roots of ancient mountains, with local relief of 61-152 meters (200-500 feet) . The north and south shores of western Lake Superior are within the Southern Province of the Shield . Topography is hilly, of somewhat lesser elevation than the Superior Province, with some local relief as great as 213 meters (700 feet). The Lake Superior basin emerged from glacier cover between 13,000 and 9,000 years ago . During that time ice-melt formed pro-glacial lakes of changing configuration and drainage patterns . The native fish community of Lake Superior is a product of this complex post-glacial history. The topography around the lake is variable, and, in many cases, dictates the productivity and fish species in a specific area . For example, the slope of the Minnesota north shore is very abrupt, both above and below the water line . The thin soils are underlain by hard igneous bedrock . The littoral zone is quite narrow, and most streams entering the lake are blocked by barrier falls short distances upstream . Spawning habitat for anadromous fishes is very limited.

13

reduction, Prevailing westerly winds on this shore push surface waters offshore, resulting in a strong upwelling of cold water from the deep . As a result, the fishery in Minnesota waters has always depended on pelagic cold-water species, with few coolwater or bottom dwelling fishes in the harvest . In contrast, the south shore in Wisconsin has a more gradual slope and a variety of depths, including extensive shallow areas . Soils are formed atop thick layers of clay and sand underlain by sandstone . Streams have extensive estuaries, and many have miles of anadromous fish spawning habitat. This area receives the relatively warm surface waters pushed by the prevailing westerlies . The fish community in this area is much more varied, including species that prefer warmer waters . Other portions of Lake Superior show similar variation in topography and temperature. About 3 percent of the U .S. shoreline of Lake Superior consists of wetlands (PLUARG 1976) . Wetlands are important as spawning and nursery areas for some fish populations in Lake Superior, but detailed information on the status and trends has not been collated . The Service has inventoried the wetlands of Minnesota and Michigan, and the Wisconsin Department of Natural Resources inventoried Wisconsin wetlands . However, at this writing, the Lake Superior basin information has not been digitized in GIS format and cannot be readily extracted from the statewide databases. The mean annual air temperature of the Lake Superior basin is low, about 17-2 .2 °C (35-36 °F), with a short growing season of 60-140 days . Annual precipitation averaged 75 .2 centimeters (29.6 inches)/year from 1900 to 1972 (Upper Lakes Reference Group 1976) . West winds (southwest to northwest) blow about 40 percent of the time with mean velocities of 7.9-14.9 (26-49 feet)/second . Wind speeds are generally higher over the lake than on land . Large waves form where wind passes over long distances of open water (Phillips 1978). The mean lake temperature does not exceed 6 .1 °C (43 °F), the coldest of the Great Lakes (Bennett 1978) . However, the amount of heat energy stored in Lake Superior in each annual cycle is the largest of any of the Great Lakes. Because of its large heat storage, Lake Superior affects the climate within the basin and beyond . Local effects include precipitation, fog, wind speed changes, and moderation of temperature variations over the land (Matheson and Munawar 1978) . Effects extend beyond the basin as the lake contributes moisture and heat to intensify storms (Phillips 1978). The native plant communities of the basin were almost entirely forest . North of the lake were extensive tracts of boreal spruce-fir forests, characterized by balsam fir, black spruce, and white spruce, with scattered thickets of deciduous species such as trembling aspen, white birch, and alders . South of the lake, the original forest cover was deciduous, dominated by sugar maple and yellow birch, with white and red pine, white and black spruce, white birch, and balsam fir as secondary species . Between the boreal and southern deciduous forests was an intermediate area dominated by white and red pines. Lake Superior has a highly irregular shoreline and lake basin . It is shaped like a wolf's head, with the snout at the mouth of the St . Louis River on the extreme western end; the eye at Isle Royale, a 97 kilometer (60-mile) long island in the northwestern portion of the lake ; and the mouth at the Keweenaw Peninsula, a 145 kilometer (90-mile) long protrusion from the south-central shore. Lake Superior has a relatively small littoral zone, especially on its northwestern and northeastern shores, where the bottom drops steeply to depths of 183-244 meters (600-800 feet) . About 80 percent of the lake is deeper than 73 meters (240 feet), roughly the depth at which "deepwater" fish species begin to dominate the community . The Canadian shore has three large, relatively shallow bays (Thunder Bay, Black Bay, and Nipigon Bay) that provide more diverse and productive fish habitat than the open lake . On the south shore, relatively shallow, productive areas include the extreme west end, Chequamegon Bay, the east side of the Keweenaw Peninsula, and Whitefish Bay on the extreme east end. The large central basin is relatively regular in configuration, with depths of 183-274 meters (600-900 feet) . The eastern basin, where the greatest depth of 406 meters (1,333 feet) occurs, is highly irregular, with a series of shoals and trenches oriented in a north-south direction . Several of the trenches exceed 274 meters (900 feet) in depth .

14

Summer thermal stratification occurs only temporarily in open waters, and is more persistent in sheltered inshore waters . Currents and upwellings are prominent features of the thermal habitat, induced by uneven heating and the prevailing westerly winds . Currents distribute summer heat gain so that maximum heat content of the water occurs near October 1, well after maximum summer air temperatures (Bennett 1978). Lake Superior rarely freezes over during the winter, so deep mixing of waters can lead to the development of homothermous water of about 2.2 °C (36 °F) to a depth of 183 meters (600 feet) . Deeper waters are at the temperature of maximum density 3.9 °C (39 °F) throughout the year (Lawrie and Rahrer 1973) . Maximum ice cover occurs around late March . Ice covers 60 percent of the lake in normal winters, 40 percent in mild winters, and more than 95 percent in severe winters (Matheson and Munawar 1978). Currents induced by temperature structure establish a persistent pattern of circulation (Matheson and Munawar 1978). Surface currents exhibit a general counter-clockwise circulation . Currents flowing from west to east are strongest along the south shore and obtain maximum strength along the northern side of the Keweenaw Peninsula . Coastal upwelling occurs along the northwest shore caused by the return flow as the prevailing westerly winds drive surface water towards the east . Upwelling also occurs in a large area in the middle of the lake . Due to upwellings along the northern shore, water temperature is consistently lower during the summer, but ice formation is delayed. The mean annual discharge to the St . Marys River was 2,100 cubic meters per second (74,130 cubic feet per second) from 1900 to 1972 (Upper Lakes Reference Group 1976), with a low of 1,773 cubic meters per second (62,576 cubic feet per second) in 1963 and a high of 2,625 cubic meters per second (92,655 cubic feet per second)in 1952 (Lawrie and Rahrer 1973) . The level of Lake Superior has been held relatively stable since 1922 by a compensation dam on the St. Mary 's River, the lake's only outlet . The amplitude of seasonal variation rarely exceeds 0 .5 meter (1 .5 feet). About 200 rivers flow into Lake Superior (Matheson and Munawar 1978) . The largest is the Nipigon River in Ontario, which drains a sub-watershed of 4,856 square kilometers (1,875 square miles) . The second largest tributary is the St . Louis River on the U .S. side . Altogether, there are about 28,968 kilometers (18,000 miles) of streams within the Lake Superior basin (PLUARG 1976). Trophic state The waters of Lake Superior are remarkably low in total dissolved solids (Matheson and Munawar 1978) . Most of the water input to the lake is derived from precipitation falling on a watershed composed of hard, impervious, and chemically resistant rocks . The drainage is by way of many short tributaries, which minimize the contact time during which mineral matter may be dissolved. Because nearly 40 percent of the basin area is occupied by the lake surface, precipitation falling directly onto the lake dilutes drainage water so that Lake Superior water is commonly said to resemble rain water (Matheson and Munawar 1978). With respect to the major ions, there is no evidence that any change in water chemistry has occurred within historical times (Upper Lakes Reference Group 1977). Primary productivity by phytoplankton is very low, about 1009 kilograms/hectare/year (900 pounds/acre/year) dry weight (Upper Lakes Reference Group 1977), near the low end of the range for freshwater ecosystems . By comparison, the open waters of the other Great Lakes are 2-5 times as productive as Superior (Vollenweider et al. 1974). Water clarity is high, with visibility typically 10 meters (33 feet) or more, indicative of the sparse phytoplankton populations. The low productivity of Lake Superior is indicated by documented fish yields . During 1916-1940, a period of high and stable yields, Lake Superior produced annual yield of 0 .9 kilograms/hectare (0.8 pounds/acre), probably near the maximum sustainable level (Ontario Ministry of Natural Resources 1987) . During the period 1879-1969, annual commercial yields averaged 0.8 kilograms/hectare (0 .7 pounds/acre) (Smith 1972) . Current annual yield is about 0 .5 kilograms/hectare (0 .4 pounds/acre), reflecting low catches of lake herring, which dominated historical yields .

15

oduction

Socioeconomics The rich tapestry of mineral, fossil fuel, water, land, and living resources of the Great Lakes Basin create economic opportunity for its human inhabitants resulting in demands upon these resources . Water resource demands include electric power generation, transportation, drinking water, agriculture, industrial processes, sanitation, and recreation. The purpose of this section is to give a broad overview of the dynamic interactions between the region's human population and its natural resources, and to describe the complexity of issues facing aquatic resource managers in the Great Lakes Basin. Great Lakes economic structure The book Great Lakes Economy: Looking North and South presents a thorough analysis of the economy of the Great Lakes region (Testa 1991) . The following material is largely drawn from this publication. Demographics and sources of personal income Almost one-third of the U.S . population resides in the eight Great Lakes States . Of these States, New York, Pennsylvania, Illinois, Michigan, and Ohio have an above average percentage of their populations living in metropolitan areas (Erdevig 1991). Average personal income in the Great Lakes States is slightly higher than the U .S . average with sources of personal income being quite similar to those in the rest of the country (Erdevig 1991). Energy issues Bournakis and Hartnett (1991) reported that regional energy consumption in 1988 was distributed as follows : petroleum, 36 .7 percent ; coal, 30 .1 percent; natural gas, 22 .8 percent; nuclear fuel, 8 .6 percent ; and renewable resources including hydropower, 1 .8 percent . Energy consumption for 1988 was distributed as follows : transportation, 23 .1 percent ; industrial 25.1 percent ; commercial, 9 .9 percent ; residential, 16.4 percent ; reject heat, 24 .8 percent ; and exports, 0 .7 percent . The industrial sector was the largest consumer of energy, with the commercial and residential sectors together equalling industrial sector consumption. The largest fossil-fueled electrical generating plant in the world is located on Lake Erie at Monroe, Michigan, however the Great Lakes region's coal resources have a high sulfur content rendering them inadequate in meeting the region's demand for clean energy. Consequently, the region imports large quantities of natural gas, oil, and low sulfur coal, making energy production vulnerable to price fluctuations . The energy statistics of the late 1980s indicate that the region is becoming more dependent on imported oil and therefore, is vulnerable to the negative effects of potential oil embargoes. Oil and gas development in lower Michigan, and potentially in northern Wisconsin, heightens the potential for pollution of ground and surface water during exploration, extraction, and transmission . Effects may include groundwater contamination by lost drilling mud, brine, and hydrocarbon seepage from leaky delivery systems . Surface water may be impaired by sediment from disturbed production sites (Michigan Chapter, American Fisheries Society, Spring 1992 Newsletter). Electrical generation-related impacts on aquatic organisms include impingement on screens, thermal enrichment of habitat, entrainment in water intake and circulation/cooling systems, extreme fluctuations in stream flow, and prevention from access to habitat by barriers such as low-head dams . Increasing demand for electricity in the Great

16

Introduction ,~I

Lakes region is expected to give rise to increased energy demand, resulting in increased generating capacity and impacts on aquatic organisms . Aquatic resource professionals and electrical generation professionals need to work together to minimize impacts upon aquatic organisms. Role of waterborne transportation Economic activity during settlement of the Great Lakes region consisted mostly of resource exploitation including fishing, trapping, mining, and timber harvest aided by water-based transport (Donahue 1991). In the mid-1900s, regional and national U .S . and Canadian economies were built on the Great Lakes-St . Lawrence Seaway transportation system . Navigation system improvements ranging from channel and lock construction to innovative vessel designs and loading-unloading equipment resulted in increased cargo carrying capacity and lower transportation costs. This same system that supports deep draft transportation from the Atlantic Ocean to Lake Superior (Thorp and Ballert 1991) also allows invasion of the Great Lakes by nonindigenous aquatic species, such as ruffe, spiny water flea, alewife, zebra mussel, quagga mussel, and sea lamprey resulting in wholesale changes in the ecosystem of the Great Lakes . These species threaten indigenous populations and are detrimental to the integrity of the ecosystem. Transportation continues to be a major factor in the modern economic infrastructure of the Great Lakes region. Waterborne commerce has served as an important means of integrating of the economies of Great Lakes States . The largest volume of shipments are of iron ore, coal, and limestone supporting the steel industry and its customers, but the ports of Duluth, Chicago, and Toledo are important for farm product shipments to other lake ports and overseas (Eldevig 1991) . To protect the integrity of the Great Lakes Basin ecosystem, aquatic resource professionals and transportation industry officials need to work together to prevent further invasions by nonindigenous species. Non-fuel mineral resources Four non-fuel minerals dominate production in the Great Lakes States : crushed stone, sand and gravel, iron ore, and portland cement . With the exclusion of iron ore, three of these products are mined in close proportion to the economic size of the region . Minnesota and Michigan iron ore, however, accounts for 98 percent of the U .S. production value of the mineral. Of the 173 million tons of all cargo shipped on the Great Lakes in 1989, 66 .7 million tons were iron ore, and 35 million tons were stone related to the iron ore and steel industry . Other industrial minerals, especially sand and gravel and crushed stone, are tied to construction activities in close proximity to the deposits. Abrasive, bromine, calcium chloride, copper, fluorite, gold, peat, salt, silver, talc, wollastonite, and zinc are also produced in the Great Lakes region and extremely important to the U .S . economy (Whaley 1991) . One copper mine is operating in the U .S. portion of the Lake Superior basin . The White Pine mine in Ontonagon County, Michigan produced 44,000 tons of copper in 1990, and employed about 1,000 workers . Unexploited deposits of copper and iron in the Lake Superior basin are being considered for mining raising concerns for aquatic habitat impacts resulting from acid mine drainage, heavy metal deposition from smelters, and disposal of tailings. Manufacturing and agricultural industries Manufacturing and agriculture are critical components of the Great Lakes regional economy . Production of motor vehicles is one of the more important industries in the Great Lakes area . In 1989, about 58 percent of all autos produced in the U .S . were assembled in five of the Great Lakes States with Michigan alone producing a full one-third. Similarly, about 56 percent of all trucks and busses were manufactured in the Great Lakes area, mostly in Michigan and Ohio (Erdevig 1991) .

17

Just over one-fifth of U.S. cash receipts from farm marketings comes from Great Lakes States with major commodities including corn, soybeans, milk, and hogs . Almost one-half of the corn, soybeans, and milk and two-fifths of the hogs produced in the U .S. come from these eight States (Erdevig 1991) . The Lake Erie basin leads the Great Lakes region in the number of farms, and in the production of hogs and pigs, sheep, chickens, corn, soybeans, and wheat. Manufacturing and agricultural industries have contributed to contamination of the Great Lakes with toxic chemicals, persistent pesticides, and sedimentation . Aquatic resource professionals need to work together with industry to minimize negative impacts upon aquatic ecosystems and to rehabilitate those areas where degradation has occurred. Forest resources Forests cover 54 percent of the Great Lakes region's land area below Hudson Bay, supporting wood products industries, essential habitat for plant and animal species and providing desirable locations for recreation and tourism activities (Leffers 1991). The forest products industry includes 5 pulp and paper mills in the U .S. portion of the Lake Superior watershed, with a combined capacity of 2,100 tons/day . About a dozen wood products mills employ more than 100 workers each in the U .S. portion of the watershed, but there are many smaller wood products enterprises. Forests are critical to the regional ecosystem, helping to stabilize soils, clean air, and circulate water . Stewardship of forest resources to maintain these important functions while supporting the wood products industries so important in Ontario, Minnesota, Wisconsin, and Michigan, is a common goal across the region . Aquatic resource professionals and foresters need to work together to minimize aquatic habitat destruction and pollution resulting from the forest products industry. National, State and Provincial parks Many natural and cultural assets of the region that are preserved and managed through separate State and Provincial and National Parks systems and form the basic elements of an outdoor recreational infrastructure (Thorp and Smith 1991) . The U.S. Department of Interior's National Park Service has jurisdiction over 5,119 square kilometers (1,969 square miles) in the Great Lakes States including : two national parks ; four national lakeshores ; one national seashore; seventeen national historic sites ; five national historical parks ; five national monuments ; one national battlefield ; one national military park ; four scenic rivers ; and four national scenic trails . Environment Canada oversees five national parks in Ontario and three in Quebec with a combined area of 3,106 square kilometers (1,211 square miles) . Great Lakes States have more than 625 State parks and Ontario has the largest absolute area of any Canadian Province reserved in Provincial parks.

Outdoor Recreation and Tourism Residents of the Great Lakes region and visitors to the area view outdoor recreation as not just a quality-of-life issue, but as a way of life . The attractiveness of the Great Lakes for outdoor recreation activities is directly connected to diversity and health of the entire Great Lakes Basin ecosystem . Outdoor recreation is of concern to both the public and private sectors, with competitive or complementary linkages between the two . For example, the private sector provides lodging for publicly administered parks, whereas, both may compete for hikers or campers . The dynamic nature of this relationship raises policy issues, especially when questions of funding or program development arise at the community level. Nearly $69 billion dollars of travel-related expenditures were attributed to the eight Great Lakes States in 1987 (Thorp and Smith 1991) . This amounted to 25 percent of the U .S. total . Ontario and Quebec received approximately $13 billion or 54 percent of Canada's $24 billion total . These expenditures supported a wide range of enterprises and

18

ntroduct~on~ .46

activities covering both the private and public establishments and facilities and including such functions as transportation, lodging, food, amusements, recreation, retail trade, and the provision of information services . Of course, all of these activities and enterprises depend upon the diversity and health of the Great Lakes Basin ecosystem which provides the infrastructure supporting the travel-related industry. Fishing Great Lakes fish provide a valuable food supply for numerous Native American Tribes who continue to fish for subsistence under court affirmed treaty rights . Subsistence fishing is most prevalent in Lake Superior and northern Lakes Michigan and Huron, especially in areas adjacent to tribal reservations . The St . Mary's River, fished intensively for centuries by Native American Tribes, continues to be used by these subsistence fishers. The Great Lakes region supports angling year-round (Thorp and Smith 1991) . These anglers exert tremendous fishing pressure on indigenous and nonindigenous fish populations in the Great Lakes and their connecting waters. According to the Service's 1991 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation, 2 .6 million Great Lakes anglers spent 25 million days in 20 million trips fishing . They spent $1 .3 billion on these trips and equipment . Trip-related expenses totaled $870 million. Of these expenditures, almost $331 million (38 percent of trip cost) was spent on food and lodging ; $173 million (20 percent of trip cost) was spent on transportation ; and $366 million (42 percent of trip cost) was spent on other items such as guide fees, equipment rental and bait . Great Lakes anglers spent $467 million on equipment . They bought $190 million worth of fishing equipment such as rods and reels; spent $29 million on auxiliary equipment such as camping equipment and binoculars ; and $247 million on the purchase of such special equipment as boats and vans. Great Lakes fishing includes not only the Great Lakes, but also their tributaries, bodies of water connecting the Great Lakes, and the St . Lawrence River south of the bridge at Cornwall . Lake Erie continues to be the most popular of the lakes among anglers with 35 percent of Great Lakes anglers fishing it in 1991, an average of 8 days per angler. Lake Michigan ranked a close second with 34 percent averaging 6 days per angler . Lake Ontario was fished by 12 percent of all Great Lakes anglers in 1991, an average of 8 days per angler. The connecting waters (St . Mary's river system, St . Clair, Niagara and Detroit Rivers) attracted 10 percent of the total Great Lakes anglers averaging 12 days of fishing per angler in 1991 . While Lake St . Clair was fished by only 5 percent of all Great Lakes anglers, they fished an average of 14 days per year, more than on any other Great Lake or connecting water. An excellent synopsis of Great Lakes commercial fishing activities is provided by Thorp and Smith (1991) . At first, the Great Lakes supported large, stable populations of fish including lake trout, lake herring, and lake whitefish. Fishing, whether by Native Americans or settlers and their commercial enterprises, was productive . But when large scale lumbering and shoreland development impaired water quality and flow conditions in tributaries and coastal marshes, spawning success declined . By 1885, exploitation by 10,000 commercial fishers began to take its toll . The U.S . Great Lakes commercial fish harvest peaked in 1899 at 119 million pounds . Invasion of the parasitic sea lamprey and other nonindigenous species, combined with impaired water quality and excessive harvest, destroyed the commercial fishery. The Great Lakes States, Native American Tribes, Service and the binational Great Lakes Fishery Commission have all played major roles in fishery rehabilitation . Effective sea lamprey control using chemical treatment provided opportunities for successful hatchery-supported planting programs . Stocking has contributed huge numbers of lake trout and Pacific salmon, in all of the Great Lakes .

19

ntroduction

The Great Lakes commercial fishery is of major economic significance to the Native American Tribes and minor economic significance to the States . As an example, in 1986 the majority of the Lake Erie commercial fishery harvest included yellow perch, walleye, rainbow smelt, and white bass with the value of the U .S. harvest at $1,050,800 (U .S. $) and Canadian harvest at $36,472,948 (Canadian $) . Great Lakes commercial fishers also play a critical role in providing the non-angling population of the Great Lakes Basin with edible fish, available at restaurants, hotels, and markets. Recreational boating In 1988, more than one-third of all watercraft in the U .S. were registered in the Great Lakes States as recreational boats (Thorp and Smith 1991). Approximately 3,527,000 recreational boats were registered in the region, but due to jurisdictional differences in registration requirements and data veracity questions, exact recreational boat activity on the Great Lakes remains unavailable. One Michigan State University/Department of Park and Recreation Resources study indicated that "boat days" on the Great Lakes grew 63 percent from 1974 - 1980 and 41 percent from 1980 - 1986 . The study also estimated that approximately 700,000 U .S . recreational boats are used on the Great Lakes each year. Boat manufacturers, retailers, marina operators and marine business suppliers all represent the diverse recreational boating industry in the Great Lakes . According to the U.S. Bureau of Labor Statistics, the eight Great Lakes States account for 6,000 private sector, marina-related jobs and 10,000 boat dealer and supplier jobs . The Detroit Boat and Fishing Show has doubled its attendance since 1981, with sales volume growing much more rapidly . In 1989, the Detroit show generated $61 .5 million in sales . The Cleveland Mid-America Boat Show, held each January, is the largest U.S . show. The Laventhol and Horvath accounting firm has predicted that the area around southern Lake Michigan (Kenosha, Wisconsin to Muskegon, Michigan) will generate 850 new shoreside dwelling units and 1,000 boat slips at marinas and residential developments each year . A 1986 Ohio Sea Grant study indicated that the "typical" Lake Erie marina had been in operation for 18 years, grossed $894,000 in annual sales and employed 5 .5 people on a full-time annual basis with a similar number of additional full time equivalents during the average 6 .6 month season . The mean annual payroll for the marinas was $100,000. Other activities The President's Commission on Americans Outdoors (1987) acknowledged that recreation is big business with a total of $262 billion of related expenditures made in 1984, $100 billion of which was categorized as outdoor recreation. Bicycle sales have been increasing in recent years, surpassing car sales . Most U.S. bicycle manufacturers are based in the Great Lakes region, mainly Illinois and Ohio . Thousands of miles of trails in the region are used by bicyclists, cross-country skiers, snowmobilers, and hikers . Great Lakes States had 54 percent of the 1991 U .S . total of trails developed from abandoned rail lines amounting to 2,775 kilometers (1,724 miles) . Ontario has also developed trails along rail corridors no longer in use. One third of U .S . downhill ski revenues are generated in Great Lakes States and more than half of the alpine ski areas in Canada are in Ontario and Quebec . Snowmobiling also accounts for large expenditures amounting to about $1 .3 billion annually . In 1987, the Great Lakes States had 742,868 registered snowmobiles ; 70 percent of the U .S. national total with Michigan, Minnesota, Wisconsin, and Illinois among the top five States . These activities impact cover vegetation. Destruction of cover vegetation varies depending upon the nature of trail-related recreational activities and the responsibility of individual recreationists . Off-road vehicles are capable of generating conditions facilitating soil erosion, if not responsibly operated . Soil erosion degrades aquatic habitat, destroying spawning, rearing, and cover areas and eventually resulting in diminished populations of species including sport fish .

20

Ecosystem Approach :.

Ecosystem Approach Ecosystem Health Concepts Natural resource agencies are going through major adjustments in their approaches to resource management, restoration, and enhancement . The terms "ecosystem" and "holistic," although not new, are now codified in international agreements and laws . The application of these concepts to resource management has been challenging and has invited the use of the analogy of human health, to explain ecosystem health issues . Although this analogy is useful for some communications, it has limits for scientific application since, for example, descriptors and definitions for ecosystem "wellness" have not been developed.

Alpena Fishery Resources office photo

Other terms used to describe ecosystem health include integrity, complexity, and diversity . Rapport (1990) stated that "integrity refers to the capability of the system to remain intact, to self-regulate in the face of internal or external stresses, and to evolve toward increasing complexity and integration ." "Integrity", as defined by Rapport, is not a static condition. Loftus and Regier (1972) related the terrestrial ecologist's concept for climax communities to the aquatic realm and the rejuvenation achieved by disturbances . Ryder and Kerr (1990) suggested that ecological communities evolve and that integrity of an ecosystem is indicated by the status of indigenous species in species assemblages . Since a variety of evolutionary changes, such as changes in species and increased complexity and diversity may be indicators of an ecosystem's "wellness," ecosystem health might be described as "ecosystem vitality in support of natural biological functions ." A focus on ability to support biological functions allows for natural and/or anthropogenic changes in species assemblages within an ecosystem that could still be described as "functionally healthy" even though stressed by harvest or habitat modification. Historic conditions or natural, undisturbed ecosystems are often suggested as targets or examples of ecosystem wellness . This would appear applicable when humans are not a major component of the landscape . However, in ecosystems where permanent human development is a major factor, humans must be considered part of the landscape . Use of undisturbed systems or pre-development time frames as descriptors of wellness or benchmarks for today's anthropogenically stressed systems undermines the ecosystem approach by excluding avoidable and unavoidable effects of humans within that landscape. The current challenge for natural resource managers is to understand the ecosystem's functional vitality and the interactions between various trophic levels . Identification of obstructions to energy flow is fundamental to assessment of ecosystem vitality and functional impairments caused by anthropogenic stresses. Implementation of the ecosystem management concept requires an understanding of natural resource goals . Society within the Great Lakes basin is now debating natural resource goals for each lake in the system . Considerations range from "a return to pristine conditions" to "intensive aquaculture ." Both extremes will be compromised since these extremes can neither be reached nor sustained .

21

Ecosystem Approach-

Society's impacts on the ecosystems of Lakes Ontario, Erie, and Michigan have been severe . Some historical effects, such as toxic contaminant loading, excessive nutrient enrichment and overharvest are reversible . Others, such as introductions of nonindigenous species, drainage basin changes, and lost indigenous species are not . Lake Superior is the least altered of the Great Lakes, but even its ecosystem has been permanently changed via drainage basin changes and introductions of nonindigenous species and, therefore, can not be returned to its historically pristine condition. While "intensive aquaculture" provides some options for resource managers, challenges, such as : maintenance of genetic diversity; maintenance of fish health within hatcheries ; facilitation of stocked fish recruitment ; and fish production costs ensure that this method alone will not suffice to ensure a healthy, productive, and diverse aquatic Great Lakes ecosystem.

Support for the Ecosystem Approach The Strategic Plan for Management of Great Lakes Fisheries, directed the preparation of fish community objectives for each of the Great Lakes . Within this plan, the following common goal was established for all Great Lakes: " To secure fish communities, based on foundations of stable self sustaining stocks, supplemented by judicious plantings of hatchery reared fish, and provide from these communities an optimum contribution offish, fishing opportunities and associated benefits to meet needs identified by society /or : wholesome food, recreation, employment and income, and a healthy human. The Strategic Plan for Management of Great Lakes Fisheries document, approved by the eight Great Lakes states, the Chippewa-Ottawa Fishery Treaty Management Authority, the Great Lakes Indian Fish and Wildlife Commission, the Province of Ontario, the Canadian Department of Fisheries and Oceans, and the Service reflects the Boundary Waters Treaty (1909) . The Canada-U S. Great Lakes Water Quality Agreement, signed in 1972 and amended in 1978 and 1987, requires an ecosystem approach to solve water quality related problems using a coordinated, binational approach. Although numerous definitions for ecosystem management have been written, the following one is applicable (USBLM 1993): "Ecosystem management is a process that considers the total environment. It requires the skillful use of ecological, economic, social, and managerial principals in managing ecosystems to produce, restore, or sustain ecosystem integrity, and desired conditions, uses, products, values and services over the long term ." The Great Lakes Water Quality Agreement, Annex 2 (1987) states that "Impairment of beneficial use(s) means a change in the chemical, physical or biological integrity of the Great Lakes System sufficient to cause any of the following: (iii) (iv) (v) (vi) (viii) (xiii) (xiv)

Degradation offish and wildlife populations; Fish tumors or other deformities; Bird or animal deformities or reproduction problems; Degradation of benthos; Eutrophication or undesirable algae; Degradation ofphytoplankton and zooplankton populations. Loss offish and wildlife habitat."

Some of these criteria may be used as stand-alone measurements . However, when applying the ecosystem approach, these criteria are also sub-sets or symptoms of (XIV) Loss offish and wildlife habitat. Loss should be defined as actual destruction and/or functional impairments (Sly and Busch 1992a) . Habitat should be defined as the biological, chemical, and physical setting needed to support all life functions of the organisms (Sly and Busch 1992a) .

22

Eco'system~pproach

Various agreements and regulations require restoration of the Great Lakes . The Great Lakes Water Quality Agreement (1987) and the Great Lakes Critical Program Act (1990) each identify "restoring and maintaining the chemical, physical, and biological integrity of the waters of the Great Lakes ecosystem or Basin," as the goal . The Great Lakes Fish and Wildlife Restoration Act (1990) identifies a scientific approach to restoring the fishery resources and the Great Lakes Critical Program Act (1990) requires "a systematic and comprehensive ecosystem approach to restoring and protecting the beneficial uses" through implementation of Lakewide Management Plans and Remedial Action Plans for designated areas within the Great Lakes basin.

Setting Ecosystem Goals and Objectives Restoration and rehabilitation require identification of target goals . Such goals and objectives have generally been available from a number of sources for specific water quality measurements . They have also been developed for some specific fish species and one habitat type (wetlands), but with the exception of the published Lake Superior and Ontario Fish Community Objectives and the soon to be published Lake Michigan and Lake Huron Fish Community Objectives, goals and objectives have not been available for fish communities and other aquatic habitat units . Very little work has been done in identifying goals and objectives at the landscape level, although development of Lakewide Management Plans using the ecosystem approach would be a big step forward. In setting fish species goals or attempting to develop fish community or aquatic habitat goals, biologists and managers are usually forced to use only such readily available information as historic production from commercial landings. This source usually provides the best available information, however, it contains major biases . As already discussed, historic conditions have changed and, with society included in the ecosystem, those conditions can not now be completely restored . Fish species have also been added and lost ; many of these changes are permanent . Therefore, predicting future population sizes or fish production from species that have been lost or replaced with new species that have been added to the fish community, requires a different approach . Suggestions are provided in the following sections.

Lake Ontario: an Ecosystem Approach Case Example To more effectively improve and maintain the Great Lakes ecosystem, present ecosystem status must be determined to focus our efforts and allow us to measure our progress . Understanding the status of available habitat is mandatory to make decisions on the need for and viability of restoration efforts intended to improve Great Lakes ecosystem integrity . Lake Ontario habitat availability, with associated levels of impairment, were determined by Busch et al. (1993). The aquatic resources of Lake Ontario are impaired according to the International joint Commission . This means that the Commission, its agents (Environment Canada and the U .S . Environmental Protection Agency) and partners (States, Provinces, and private and public agencies) have reached the conclusion that anthropogenic stresses are having a significant negative impact on the ecosystem. Efforts were made to evaluate the status of the Lake Ontario ecosystem . The general problem is presented in Figure 7 . This report focuses on the assessment of functional impairments to the habitats of the Lake Ontario ecosystem . Physical changes to the basin were inventoried. Chemically-caused stresses were reviewed . General impacts on the ecosystem's health caused by nonindigenous species were also evaluated .

Figure 7 . Conceptual representation of the degradation of an ecosystem and the recovery due to restoration initiatives (from Council of Great Lakes Research Managers 1991) .



Ecosystem

J

roach

Habitat classification methodology Table 2 . The hierarchy of aquatic habitat classification (modified from Sly and Busch I992b) . SYSTEM Lake Ontario j

SUB-SYSTEM

DIVISION

Open water

SUB-DIVISION

Circulatory basin

I (Open Water)

I Deep water reef, >25 meters Fluvial deposition zone Major embayment, 25 meters deep Relict trench Sub-basin, 25 meters .. ..

J

I N e a r s h o re

Shoreline

J

I

'Each Class level descriptor had three modifiers - biological, chemical, and physical.

I I

23 4

4S ~ °. ~.R

CLASS' [Water column=Wc, Substrate = S, Plant material =Pm] We, S Wc, S, Pm Wc,S, Pm

Wc, S We, 5, Pm Wc, S, Pm We, S [Wc, Water quantity = Wq, S, Pm, Plant cover = Pc] (Shoreline for 100 m, developed littoral zone 73 cm -63-73 cm

'- 53-fi3 cm

50

43-53 cm

-----------

40

30

-----------------



20

-- --------------------------

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Figure 66 . Average sea lamprey wounding on various sizes of lake trout caught during index gill net surveys from Michigan and Ontario statistical districts of Lake Huron, 1986-1992 (Ebener 1994) .

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Figure 67 . Millions of predator fish stocked annually in Lake Huron, 1968-1992 . Species include lake trout, walleye, brown trout, chinook salmon and coho salmon (Ebener 1994).



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While there are no data on sport harvest of chinook salmon in most of Ontario waters, fisheries do exist in the North Channel, Manitoulin Island, and Bruce Peninsula areas of the lake . Sport harvest in southern Georgian Bay has ranged from 13,600 fish in 1992 to 18,000 in 1991. Sport harvest estimates in Michigan waters are incomplete for several years, but creel surveys conducted at all major fishing ports and locations during the years 1986-1988, reported catches ranging from 84,390 in 1986 to 105,406 in 1988 (Rakoczy 1991). Considerable biological data gaps exist in regard to chinook salmon in Lake Huron . Little biological information is available to describe growth during the open water phase of their life cycle . Most growth data are collected from prespawning fish at the weirs . These data indicate relatively stable growth rates since the 1970s . In addition, food habits of chinook salmon are not well known but presumed to be primarily limited to alewife and rainbow smelt. The extent of natural reproduction in Lake Huron is not known . Large numbers of adult chinook are observed in most Ontario streams known to support rainbow trout (steelhead) reproduction . While most of the major streams tributary to Michigan waters of Lake Huron are blocked by dams, there is evidence of some natural reproduction. Wild young-of-the-year chinook have been captured in St . Martins Bay in northern Lake Huron, and ongoing studies in the central basin are producing estimates of wild production as high as 30 percent. Sea lamprey wounding rates are 18-33 per 100 chinook salmon in the northern portion of the lake, but research is needed to determine the lethality of these attacks. Michigan Department of Natural Resources stocked an average of 509,000 yearling coho from 1968-1989 (Figure 67) . The 1969 harvest in Michigan waters was estimated at 34,000 . However, poor survival of subsequent year classes coupled with concerns regarding negative interaction with other riverine species prompted cessation of stocking in 1986 . Few data are available on the fishery in Ontario, but it is considered a minor contributor to the sport fishery. The future of coho salmon in Lake Huron, as defined by the fish community objectives, is to persist at levels attainable by natural reproduction alone (Lake Huron Alpena Fishery Resources Office photo Committee 1993) . Little management effort is directed at coho salmon and as a result, very little biological information exists regarding the species in Lake Huron. Pink salmon have never been stocked in Lake Huron but have established themselves as a sport fishery of regional significance . Existing pink salmon populations have become established as a result of immigration from Lake Superior. Pink salmon were first introduced in Thunder Bay, Ontario in 1956 (Scott and Crossman 1973), and first identified in the Carp River, Lake Huron in 1969 (Parsons 1973). Sport harvest of pink salmon fluctuates bi-annually, with the significant harvests coming in the odd years (1985, 1987, 1989, etc.) . No recent studies have been conducted in Ontario waters, and limited creel data suggest that pink salmon are either not abundant, or are not sought by local anglers . Very limited biological information has been developed on pink salmon in Lake Huron . Abundance is monitored only through creel surveys in Michigan, and no data exist on survival, growth, or sea lamprey wounding rates. Rainbow trout are viewed by the Lake Huron State and Provincial management agencies as having an increasing role in the fish community. There are three different types of rainbow trout are being managed for in Lake Huron .

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"Domestic" rainbow trout occupy open waters of the lake on a year-around basis and are stocked in harbors and off breakwalls to provide excellent angling opportunities, with little potential for natural reproduction . "Steelhead" are a genotype of rainbow trout that spend most of their life in the open water of the lake but enter tributaries to spawn . A Lake Michigan "winter-run" steelhead is the strain currently being stocked in Lake Huron . Skamania is a strain of steelhead that enters streams earlier than the conventional steelhead, and generally spawns earlier. Stocking of rainbow trout resulted in establishment of naturalized populations in many locations of Lake Huron by 1930 (Berst and Spangler 1973) . Since 1986, annual stocking of rainbow trout (domestic, steelhead, and Skamania) has averaged 1".85 million, and has been increasing in recent years (Figure 67) . Various life stages have been planted (fry, fingerling, and yearling) but survival appears best in the larger yearling smolts . Beginning in 1993, stocking of large smolts will replace fry and fingerling plants in Michigan waters of Lake Huron, to the extent possible . Skamania were stocked in Michigan waters from 1983-1991, but stocking was discontinued due to concerns about survival in the face of warm summer stream temperatures, and genetic interaction with existing steelhead populations . Ontario has stocked Skamania in Georgian Bay, but results have not been encouraging. While rainbow trout provide important seasonal fisheries in some locations, harvests are still a small portion of total lake-wide salmonid harvest . Nearly one-half of the total Michigan harvest of rainbow trout is from the AuSable River. Harvest data from the Ontario side of the lake is limited but catch rates have been documented from the Saugeen and Bighead Rivers. Abundance of naturally reproducing rainbow trout has been declining in many regions of Ontario waters of the lake. Reasons for these declines have not been identified, but may be the result of poor year-class production during the late 1980s, coinciding with low stream flows and high water temperatures . There is no information to describe survival or growth of rainbow trout in Lake Huron . Sea lamprey wounding of rainbow trout decreases from north to south, coinciding with sea lamprey abundance. Brown trout constitute a relatively minor role in the overall Lake Huron salmonid community, but do provide an important regional fishery in areas such as Thunder Bay, Michigan, and Georgian Bay, Ontario . Due to declining harvests, Michigan Department of Natural Resources has initiated a strain evaluation study in Thunder Bay to enhance that fishery . In addition, management strategies have been altered to improve early survival . Stocking in Thunder Bay has been delayed until June, when alewife abundance is greatest, to buffer predation effects on early survival . There are no data to describe lake-wide abundance, growth, or food habits of brown trout in Lake Huron. Most of the natural reproduction of brown trout in Lake Huron is on the Ontario side . Lack of homing and instream recruitment on the Michigan side may be due to genetics, lack of imprinting, competition for spawning and rearing habitat by other salmonids, or a combination of factors. Brown trout seem to be less susceptible to sea lamprey wounding than many of the other Lake Huron salmonids as the wounding rates are relatively low. Atlantic salmon are considered a minor component of the Lake Huron fish community, and stocking is suggested only for experimental purposes. An experimental stocking program has been initiated in the St . Mary's River, the results of which have not been analyzed. Due to the severity of the sea lamprey problem in Lake Huron, an entire section of this report, and in Ebener (1994), is dedicated to describing the situation . The discussion is based on information provided by Morse et al. (1994) . Sea lamprey control was initiated in Lake Huron tributaries in 1960, but due to budget constraints control was interrupted from 1963-1965 . Routine treatments were resumed in 1966, and have continued annually . Abundance of sea lamprey decreased significantly following the routine treatments and remained stable through 1982 . However,

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beginning in 1983 abundance began to increase as a result of increased production of transformers in the St . Mary's River, the largest tributary to Lake Huron. Without question the sea lamprey problem in northern Lake Huron, associated with increased production from the St. Mary ' s River, is the most severe impediment to a healthy fish community in the lake . Although sea lamprey control efforts on all Lake Huron tributaries, excluding the St . Mary's, are comparable with the other Great Lakes, there are more parasitic sea lamprey in Lake Huron than in the other lakes combined (Schleen 1992) . Schleen (1992) noted that one in five chinook salmon caught in Lake Huron has a sea lamprey attached to it, compared to one in one hundred in the other lakes . As discussed in the section on lake trout, sea lamprey attacks on this species are having devastating effects on the rehabilitation effort . In addition to lake trout and chinook salmon, sea lamprey are now impacting other fish populations. Due to the size of the St . Mary's River, conventional chemical treatment/trapping strategies are not practical for controlling this parasite . As a result, in 1991 the Great Lakes Fishery Commission directed the Sea Lamprey Integration Committee to recommend alternate control strategies for the St . Mary's River. A St. Mary's River Control Task Group was formed to make recommendations for control of sea lamprey in the river for 1992-1995, addressing the following : 1) identify control options; 2) predict the effectiveness and costs of the control options ; and 3) identify information needs required to assess the control options prior to and after implementation . A multi-faceted integration program has been devised with both short and long-term strategies.

Nearshore fish community Native American Tribes inhabiting the Lake Huron region relied heavily on lake sturgeon as a food source and actively sought them in several regions (Kinietz 1940) . Early European commercial fishers considered lake sturgeon to be a nuisance, but when the market value of their flesh and roe was realized, harvest soared . Lake-wide commercial harvest in Lake Huron was 453,000 kilograms (997,000 pounds) in 1885, with 80 percent of the catch coming from Canadian waters . By 1928, commercial fishing for sturgeon was prohibited in Michigan waters of the lake. The rapid increase in harvest effort in the late 1800s, coupled with construction of dams in the early 1900s, which blocked access to spawning and nursery waters on many of the historically important sturgeon spawning streams, resulted in a precipitous decline in abundance in Lake Huron (Ono et al. 1983) . Some commercial harvest continues in the North Channel and the southern main basin of Canadian waters . While no documented spawning populations are known in Lake Huron, the lower 30 kilometers (20 miles) of the Mississagi River contain suitable spawning habitat and may be producing the sturgeon fished in the North Channel . Sturgeon spawning is known to occur in the St . Clair River and may be producing the fish harvested in the southern main basin. No active management plans exist for lake sturgeon in Lake Huron, but there is considerable inter-agency interest in a recovery program . Inventory and protection of remnant stocks, as well as restoration and rehabilitation of habitat are the main focus of current activities . The Michigan Department of Natural Resources has developed a draft recovery plan for their waters, including Lake Huron, and it is being reviewed by other interested agencies .

all

Yellow perch are an important component of sport and commercial harvest lake-wide and are widely distributed in Lake Huron . Commercial catch of yellow perch has been relatively stable since 1920, averaging 370,000 kilograms (814,000 pounds) (Baldwin et al. 1979) . Estimates of sport harvested yellow perch in U .S. waters are restricted to certain areas such as Saginaw Bay, Les Cheneaux Islands, St . Mary's River, DeTour-Drummond Island and a few other ports . Additionally, estimates are considered conservative because basin-wide creel surveys are not conducted, and the ice fishery is not always surveyed . Reported harvest has ranged from 200,000 fish in 1989 to 1 .0 million in 1987. Abundance estimates are restricted to Saginaw Bay and the Les Cheneaux Islands . Abundance of yearling and adult fish in both regions appears to be declining in recent years. Growth rates vary between areas of the lake . Yellow perch in Saginaw Bay have shown a general decrease in growth rate over time that appears to be linked to water quality changes and subsequent changes in food supply . Eutrophication of Saginaw Bay waters appears to be responsible for near elimination of the large burrowing mayfly considered to be important for perch growth in those waters (Haas and Schaeffer 1992) . Growth of yellow perch in other regions of U.S. waters, where data are available, appears stable and near the state-wide average. The goal of walleye management in Lake Huron is to restore the species to its historic importance as the dominant near-shore predator. Walleye have always been an economically important species for both commercial and sport fisheries. Prior to the collapse of the Saginaw Bay walleye fishery in the late 1940s, lake-wide harvests of 450,000 to 900,000 kilograms (990,000 to 1 .98 million pounds) occurred regularly. With the recovery of the Saginaw Bay fishery, current lake-wide harvest averages 329,000 kilograms (721,000 pounds), and is equally split between sport and commercial fishers . Commercial walleye fishing exists only in Ontario waters, since Michigan halted its commercial walleye licensing in 1967 (Baldwin et al. 1977). Stocking programs for reestablishment of the walleye fishery in Lake Huron were initiated in Saginaw Bay in 1978 (Michigan Department of Natural Resources), North Channel and Georgian Bay in 1984 (Ontario Ministry of Natural Resources), and by the Chippewa-Ottawa Treaty Fishery Management Authority in the northern waters in 1985. Both fry and fingerling stocking strategies have been employed but fingerling stocking is considered to be the most efficacious . Sport harvest of walleye in Saginaw Bay has increased dramatically from near zero in 1980, to 80,000 per year in the early 1990s . Currently it is estimated that there are 884,000 sexually mature (age-3 and older) walleye in Saginaw Bay . Other areas where walleye recovery efforts have been successful include Thunder Bay and St . Martin Bay. Growth rates of Lake Huron walleye have remained relatively stable since recovery efforts were initiated, although there is some variability between areas of the lake . Walleye from St . Martin Bay grow somewhat slower than in either Thunder Bay or Saginaw Bay . In spite of the abundance of walleye in Saginaw Bay, the fact that growth has remained constant indicates that the carrying capacity has yet to be reached. Some natural reproduction has been documented in the St . Mary's and Cheboygan River system in the north, and some reproduction is occurring in the Saginaw Bay tributaries . While the reproduction occurring in the St . Mary's and Cheboygan Rivers is sustaining a population, the extent of the contribution in the Saginaw Bay region is not known . Attempts have been made by the Michigan Department of Natural Resources to quantify the "wild" component of the Saginaw Bay walleye population but results have not been conclusive . Public perception that walleye populations in Saginaw Bay are being maintained by the stocking program has hindered Michigan Department of Natural Resources efforts to fully evaluate the question through an "alternate-year stocking program" .

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In areas of Lake Huron where suitable habitat remains for reproduction and nursery areas, northern pike are a prominent predator and desirable sport fish. Unfortunately, loss of coastal marsh habitats throughout the lake has been a major factor contributing to decline of this species. Historically, a significant commercial harvest of northern pike existed in the Canadian waters of the Georgian Bay and North Channel. Lake-wide commercial harvest in 1921 was 136,000 kilograms (299,000 pounds) (Baldwin et al. 1979), but has steadily declined since that time . Commercial harvest of northern pike in Michigan waters ceased in 1966. Sport harvest data for northern pike is incomplete because creel surveys are not conducted annually or on a lake-wide basis in many areas due to budget constraints of the various agencies . Most (95 percent) of the reported sport harvest comes from the St . Mary's River/Drummond Island area of northern Lake Huron. Information regarding abundance of northern pike in Lake Huron is limited, and generally obtained only through incidental catch in surveys for other species . There appear to be sizeable populations in the St . Mary's River system, St. Martin Bay, around the Les Cheneaux Islands, Georgian Bay, Cheboygan, and Saginaw Bay . Again, availability of spawning habitat is the main criteria for maintaining populations of this species . Efforts are being made to restore access to remaining marshes in U .S. waters. Limited data are available on abundance of muskellunge in Lake Huron . Some reproducing populations exist in Canadian waters of Georgian Bay, the North Channel, and the St . Mary's River. Nearshore fish community (warmwater bays) Channel catfish inhabit nearshore waters of the warmer Lake Huron bays . Commercial harvest of channel catfish has increased since 1952, especially in Saginaw Bay, where nearly 90 percent of the current harvest occurs . Sport harvest is not closely monitored but is thought to be below its potential, due primarily to Michigan Department of Public Health consumption advisories for Saginaw Bay. In summary, little biological information is available on channel catfish in Lake Huron, with the exception of Saginaw Bay. Smallmouth bass are present in most nearshore waters of Lake Huron, and are a highly desirable sport species . In Ontario waters, smallmouth bass may be the single most important sport species . Michigan ranks them as one of the top ten sport species sought by anglers. Very little biological information exists on smallmouth bass in Lake Huron . It is generally believed that reproductive success, and consequently overall abundance, is directly related to water temperatures . Year class strength varies depending on annual climatic conditions at the time of reproduction and early rearing . Summer temperatures also affect annual growth rates. Distribution and abundance of largemouth bass is considered to be much more restricted than smallmouth bass, and probably restricted to the inner Saginaw Bay and similar habitats around the lake . They are considered to be locally important to sport fishers in Saginaw Bay. Rock bass, pumpkinseed, black crappie, bluegill, and both longear and green sunfish are considered to be important centrarchids to sport fishing in some areas . Rock bass are probably the most abundant, making up approximately 75 percent of the centrarchid harvest in Michigan waters of Lake Huron in some years .

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Causes of Changes in Lake Huron Fishery Resources and Management Strategies Causes of changes in Lake Huron fishery resources Overexploitation, habitat impairment, and loss and instability of fish stocks due to invasion of undesirable aquatic species have combined to cause declines in many of the indigenous Lake Huron fish species . Human development and the perturbations resulting from habitat alteration for the benefit of non-aquatic inhabitants have been instrumental in declines of species relying on the near-shore environments and tributaries for critical phases of their respective life cycles . Blocking of streams by hydro-power facilities ; draining and diking of wetlands for residential and agricultural development ; and physical alteration to the system to provide shipping industry access to urban centers on the Great Lakes, have in many cases caused changes that are almost impossible to correct . Disregard or oversight of the importance of genetic diversity and integrity of indigenous species has led to reduced fitness of stocks . Hatchery programs directed at restoring indigenous species or filling niches vacated by extirpated species have, in some cases, actually resulted in accelerating declines of some of those stocks. Certainly no one factor can be blamed for the losses or declines that have occurred, but each in its own way has been instrumental . While any one of the factors may have been overcome, the combined effects have been more than the system could handle and the fish community suffered the consequences.

Management strategies in Lake Huron The Strategic Plan for Management of Great Lakes Fisheries charged the Great Lakes Fishery Commission's, Lake Huron Committee with development of objectives for definition of what the fish community of the lake should look like in the future, and to develop means for measuring progress . These objectives were drafted in 1993 and accepted by the Great Lakes Fishery Commission in 1994 (Lake Huron Committee 1993) . As defined, the overall fish community objective for Lake Huron is to ; over the next two decades restore an ecologically balanced fish community dominated by top predators and consisting largely of self-sustaining, indigenous and naturalized species capable of sustaining annual harvests of 8.9 million kilograms (19.6 million pounds). Fish Community Objectives for Lake Huron presented twelve statements summarizing actions needed to attain the desired fish community: Establish a diverse salmonine community which can sustain an annual harvest of 2 .4 million kilograms (5.3 million pounds), with lake trout the dominant species and anadromous (stream spawning) species also having a prominent place. Re-establish and/or maintain walleye as the dominant coolwater predator in its traditional area with populations capable of sustaining a harvest of 0.7 million kilograms (1 .5 million pounds). Maintain the yellow perch as the dominant nearshore omnivore, and sustain a harvestable annual surplus of 0 .5 million kilograms (1 .1 million pounds). Maintain the northern pike as a prominent predator throughout its natural habitat ; maintain the muskellunge in numbers and at sizes which will safeguard and enhance its special status and appeal ; sustain a harvestable annual surplus of 0.1 million kilograms (0.2 million pounds) of esocids. Maintain channel catfish as a prominent predator throughout its natural habitat; and sustain a harvestable annual surplus of 0.2 million kilograms (0 .4 million pounds).

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Maintain the present coregonine diversity ; manage stocks of lake whitefish and ciscoes at levels capable of sustaining annual harvests of 3.8 million kilograms (8.5 million pounds); restore lake herring to a significant level, and protect, where possible, rare deepwater coregonids. Sustain smallmouth and largemouth bass and the remaining assemblage of sunfishes at recreationally attractive levels over their natural range. Increase the abundance of lake sturgeon to the extent that the species is removed from its threatened status (U S. waters); maintain or rehabilitate populations in Canadian waters. Maintain a diversity of prey species at population levels matched to primary production and to predator demands. Reduce sea lamprey abundance to allow the achievement of other fish community objectives ; obtain a 75 percent reduction in parasitic sea lamprey by the year 2000 and a 90 percent reduction by the year 2010 from present levels. Maintain and promote genetic diversity by conserving locally adapted strains and by ensuring that strains offish being stocked are matched to the environments they are to inhabit. Protect and enhance fish habitat and rehabilitate degraded habitats ; achieve no net loss of the productive capacity of habitat supporting Lake Huron fish communities and restore damaged habitats ; and support the reduction or elimination of contaminants.

Alpena Fishery Resources Office photo



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aice Mtchiga

Historic and Current Status of f Fishery Resources and Trends Appendix II lists species composing the Lake Michigan fish community (past and present), and current status of stocks being monitored . Lake Michigan's indigenous fish community resulted largely from recolonization of species and evolution of endemic species following retreat of the Laurentian Glacier, about 11,000 years ago . By the European settlement era, 79 fish species inhabited Lake Michigan and an additional 40 were recorded from tributaries (Bailey and Smith 1981) . The most abundant and well-known species were those commercially fished . At the time of first contact (after 1650) between Native American Tribes and Europeans in the Lake Michigan basin, Native Americans were fishing for lake whitefish, lake trout, and lake sturgeon with a variety of gears : nets (made of nettles), spears, hook and line, and weirs (in streams) (Kinietz 1940) . Wells and McLain (1973) give a detailed account of the non-aboriginal fisheries through 1970 . The earliest fishery was primarily for lake whitefish, which were abundant inshore . By 1879, the first year of reliable records, lake whitefish were already considered depleted in some nearshore locations and other species became commercially important : sturgeon, lake trout, lake herring, and deepwater coregonids (Figure 68).

.Chubs ' Lake herring Lake whitefish ake trout ellow perch 1890

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Figure 68 . Annual harvest of the major commercial fish species from Lake Michigan, 1890-1993 (data from Lake Michigan Committee).

Lake Michigan's food web can be viewed as consisting of two separate but overlapping parts, the pelagic food web associated with off-shore, open water, and the benthic food web associated with the bottom . Both originate with planktonic algae and phototrophic bacteria produced in the photic zone surface waters, where light penetration is adequate for photosynthesis . The pelagic food web is based on consumption of algae by invertebrates (zooplankters); mostly cladocerans and copepods, including copepod species that prey on other small invertebrates . The benthic food web is based on direct conversion of detritus (decomposing algae and other organisms) which rains down to the bottom from the photic zone . Especially prominent in the benthic zone are two large forms, Mysis relicita (Mysis) the opossum shrimp, and Diporieia hoyi (Diporieia), an amphipod . Mysis, besides feeding on detritus, also migrates

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vertically at night and preys on zooplankton . Mysis and Diporieia evolved during deglaciation and their distribution is now discontinuous and restricted to large, deep, glacial-scoured lakes, like the Great Lakes . Because of their relatively large size and high lipid levels, these macrobenthic invertebrates have made the benthic food web an important highenergy food source in offshore waters for all but larval and juvenile fishes. In the historic fish community small cladocerans and copepods in the pelagic zone supported production of larval and juvenile fish : deepwater coregonids, lake whitefish, lake herring, deepwater sculpin, and burbot, all of which have pelagic larvae. None of the common indigenous species fed exclusively, as adults, on small particles like cladocerans and copepods. Adult deepwater coregonids and lake whitefish became benthivores, feeding primarily on Mysis and Diporieia, and the lake trout and burbot became piscivores, feeding primarily on other fish, such as ciscoes and sculpins. The lake herring, continued to use the pelagic food web as adults (Dryer and Beil 1964). Offshore fish community Lake herring and deepwater coregonids were the most abundant fishes in the off-shore pelagic community, feeding on zooplankton along with the pelagic fry and young of many other important fishes (Crowder 1980) . This characteristic of indigenous fishes to produce pelagic fry might have made them vulnerable to excessive predation when the introduced alewife, became prominent in the 1950s . Lake trout also fed extensively on herring and young deepwater coregonids in the warmer pelagic zone . Among Great Lakes piscivores, lake trout was the species best adapted to occupy all depths of the lake. In the benthic community, deepwater coregonids, deepwater sculpin, Mysis, and Diporieia created a food web supporting lake trout and burbot, the major deepwater piscivores . The deepwater coregonids were a complex of six closely related species, two of which suffered severe declines from overfishing before the turn of the century (Smith 1968). Burbot were also abundant and probably competed with lake trout for prey, but catches of this important predator were infrequently recorded because of low market demand . Lake trout and burbot also likely preyed on each other as observed in Lake Superior (Bailey 1972; Conner et al. 1993). Lake Herring production often was the highest of any species in the early Lake Michigan fishery. During the early 1900s harvest reached 11 million kilograms (24 million pounds) (Figure 68) . Production dropped shortly thereafter and has never returned to such levels . The annual catch averaged around 4 million kilograms (9 .0 million pounds) from 1901-1918 and about 2 million kilograms (4 .5 million pounds) from 1919-1938 . Except for a brief resurgence in catch in the early 1950s, lake herring harvest continually declined to almost nothing by the 1970s . Green Bay has contributed 87 percent of the lake herring harvest in Lake Michigan since about 1936 when reliable records of Green Bay's portion of the catch were first available (Smith 1956). Early declines of lake herring in Lake Michigan were largely a result of heavy exploitation, however, pollution must have been a factor in southern Green Bay. It is likely that the resurgence of rainbow smelt to considerable abundance by the early 1950s, in combination with the explosive increase of alewife which began in the mid-1950s, have reduced lake herring to its present insignificance in Lake Michigan. Seven species of deepwater coregonids were once recognized from the Great Lakes, but Lake Michigan was the only lake to contain all seven (Koelz 1929 ; Smith 1964) . The plastic morphometric and meristic characters of the different species made their taxonomic status questionable and their identification as juveniles difficult, if not impossible (Smith and Todd 1984) . The bloater, smallest of the seven species, is the only cisco that has persisted in significant harvestable quantities in Lake Michigan since the 1950s (Brown et al. 1987). Hence, the term bloater and chub are now nearly synonymous in reference to the commercial harvest in Lake Michigan .



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1973

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Figure 69. Forage biomass in Lake Michigan, as assessed by U .S .Fish and Wildlife Service bottom trawls, 1973-1993. Deepwater cisco harvest ranged from around 0 .9-2 .7 million kilograms (2-6 million pounds) annually from the early 1900s to the early 1950s (Figure 68) . In the 1950s and early 1960s, annual harvest averaged approximately 4 .5 million kilograms (10 million pounds) with a peak of 5 .4 million kilograms (12 million pounds) . By the mid-1950s, lake trout and burbot populations were all but extinct, which nearly removed predatory demand on ciscoes ; commercial exploitation switched to deepwater coregonids from the collapsing lake herring stocks . Shortly after the peak population explosion and die-off of alewife in the late 1960s, deepwater coregonids experienced year class failure that drove them to near extinction in the 1970s (Figure 68) . Environmental conditions favoring recruitment of bloater over alewife, and increasing predation on alewife by stocked trout and salmon populations, allowed the bloater population to rebound significantly during the 1980s to the extent that bloater are the most abundant forage again in Lake Michigan (Figure 69). Rainbow smelt and alewife are the present nonindigenous components of the offshore pelagic forage community. Rainbow smelt in Lake Michigan originated from a planting in Crystal Lake, Michigan, in 1912 (Van Oosten 1937). The first rainbow smelt reported in Lake Michigan was caught in a commercial net in 1923, near the mouth of the stream through which Crystal Lake drains into Lake Michigan . Rainbow smelt occupied the entire lake by 1936 (Wells and McLain 1972) . Commercial production, which had been centered in Green Bay, increased from 39,009 kilograms (86,000 pounds) in 1931 (the first year of record) to 2 .2 million kilograms (4 .8 million pounds) by 1941 (Figure 68) . Harvest dropped abruptly to 2,268 kilograms (5,000 pounds) in 1944 as a result of an epidemic die-off (apparently caused by disease) in the winter of 1942-1943 (Van Oosten 1947) . Rainbow smelt stocks quickly recovered and produced a harvest of 4 .1 million kilograms (9 .1 million pounds) in 1958 . Abundance dropped again and has stayed fairly stable since the 1970s . Harvest, which is driven more by market conditions, has remained relatively low until the early 1980s when Lake Erie rainbow smelt production dropped .

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The first alewife was recorded in Lake Michigan in 1949 (Miller 1957) . By 1957, alewife had dispersed throughout the lake . The population increase was explosive in the late 1950s and early 1960s . Commercial production increased from 99,790 kilograms (220,000 pounds) in 1957 to 2 .1 million kilograms (4 .7 million pounds) in 1962 and reached a peak of 19 million kilograms (41 .9 million pounds) in 1967 . Major die-offs of alewife occurred in the spring after spawning and caused major refuse problem for public beaches and even plugged some water intake structures . The abundant and seemingly uncontrollable alewife was also the impetus for introducing Pacific salmon in Lake Michigan . As the trout and salmon stocking program developed a large predator biomass, predation and environmental conditions, such as cold winters, resulted in reduced alewife recruitment in the early 1980s and an eventual decline in their abundance to an estimated 40,000 metric tons (43,956 short tons) (Figure 69). The lake trout was the most valuable commercial species in Lake Michigan from 1890 until the mid-1940s, and supported the largest lake trout fishery in the world before it was driven to extinction by nonindigenous sea lamprey attacks in the 1940s and 1950s . Beginning in 1890, the fishery was characterized by exceptional stability for several decades (Wells and McLain 1972) . In 1890-1911 the catch was consistently high, averaging 3 .7 million kilograms (8 .2 million pounds) . The average annual yield then dropped to 3 .2 million kilograms (7 .0 million pounds) in 1912-26, and declined further to 2 .4 million kilograms (5 .3 million pounds) in 1927-1939 . The trend was reversed in 1940-1944 when the catch averaged 3 .0 million kilograms (6 .6 million pounds) . The year 1945 marked the beginning of a precipitous decline that culminated in the extermination of the species by 1956 . Though fishing pressure was increasing in intensity during the 1940s, sea lamprey predation remains the prime culprit in the dramatic decline of Lake Michigan's indigenous lake trout (Coble et al. ; Hile et al. 1951 ; Eschmeyer 1957 ; Holey et al. 1995). Control of sea lamprey was the first step necessary to restore lake trout in the Great Lakes . In Lake Michigan, sea lamprey spawning runs had been confirmed in 79 streams by the end of 1949 (Smith and Tibbles 1980) and initial attempts to control the burgeoning sea lamprey population were targeted on these migrations ; first with mechanical weirs (7 were installed in streams along the west and south shore) and later with more effective electromechanical weirs (65 of these combination electrical barrier and mechanical traps were installed and operational by 1958) . The impact of these control devices was limited due to a variety of mechanical, physical, and biological problems and many were operated only for a few years . The development of a chemical method to destroy the stream-dwelling larval phase of the sea lamprey (Applegate et al. 1961) hastened the demise of the weirs. Only three weirs remained operational beyond 1960, as assessment devices to measure annual changes in the number of spawning migrants. Experimental chemical treatment of tributaries to Lake Michigan began in 1960 and by the close of 1965 most lamprey-producing streams had been treated once . The completion of this first round of treatments and the resultant destruction of stream larval lamprey populations caused the number of adult lampreys captured at index electric weirs to decline by 80-90 percent by 1966. Reintroduction of lake trout began in 1959, with the release of 35 .6 thousand fish on the Sheboygan Reef (Holey et al. in press) . Major hatchery production of lake trout from the National Fish Hatchery System began in 1965 with 1 .07 million fish . The numbers of Iake trout stocked into the lake increased steadily until the early 1970s, then leveled off at about 2.4 million fish . As the sport fishery in Lake Michigan grew, so did lake trout harvest . In the early 1980s, a Federal Court upheld lake trout harvest rights of the Chippewa/Ottawa Indians granted in the 1836 Treaty. Chippewa/Ottawa Indians commercial lake trout fishery harvest has averaged around 1 .1 million kilograms (2 .4 million pounds) (Figure 70). The environmental catastrophe created by the previously mentioned millions of dead alewife on the beach, caused resource managers to search for solutions . The opportunity made it easy to argue for stocking new species to prey on abundant alewife and provide put-grow-and-take angling opportunities (Tody and Tanner 1966) . Coho salmon and chinook salmon stockings, were initiated in 1966 and 1967 respectively . Other non-indigenous trout and salmon stocked since the late 1960s include Atlantic salmon, rainbow trout, and brown trout, tiger trout (brook trout X brown trout) and splake (lake trout X brook trout) . Brook trout, indigenous to the tributary streams of Lake Michi-



119

ke

16 0

Chinook salmon

ZR2

Rainbow trout

® Coho salmon

4

Lake trout

Brown trout

YEAR

Figure 70. Harvest of the major sport fish species from Lake Michigan, (1890-1993) (data from Lake Michigan Committee) .

Brown 9. iChinook

Rainbow ®Coho

YEAR

Figure 71 . Millions of trout and salmon stocked annually in Lake Michigan,(1976-1993) . Species include lake trout, Atlantic salmon, splake, chinook salmon, coho salmon, brown trout, and rainbow trout (data from Lake Michigan Committee) .

Michigan,

120

Lake Michigan

gan, were also stocked . Numbers of salmon and trout stocked increased through the 1970s, but have remained fairly constant since 1980 (Figure 71) . A phenomenal sport fishery followed stocking . As the Pacific salmon reached maturity, lakewide harvest increased dramatically . Interest in the fishery that developed stimulated tourism and recreation economies along the lake shore previously diminished by dead alewife on the beach . Chinook salmon, with its large size and well known fighting reputation soon became the focus of the sport fishery . Total harvest of trout and salmon increased steadily to a peak of 7 .3 million kilograms (16 .1 million pounds) in 1986 (Figure 70). Average annual harvest during the early 1980s from this multi-species fishery exceeded historical averages for the lake trout fishery by at least three times . Many factors could have contributed to higher harvests in recent years, including : (1) an increase in the primary productivity of the lake due to nutrient enrichment associated with pollution and waste discharge ; (2) a more efficient use of food resources by multiple versus single species ; (3) higher vulnerability of salmon due to their habit of returning to natal streams ; (4) a higher production to biomass ratio for salmon than for lake trout ; and/or (5) higher allowable mortality rates, since hatcheries required fewer broodfish than would selfsustaining populations. In 1988 the first of a series of spring die-offs of chinook salmon occurred, closely matching major drops in catch, which started in 1987 in Michigan waters and 1988 in Wisconsin waters . Many of the dead salmon exhibited severe infections of bacterial kidney disease . The causes of disease outbreak remain unknown . One hypothesis is that inadequate nutrition resulting from a scarcity of alewife triggered disease onset . Another hypothesis is that the disease spread as a result of hatchery rearing practices . Regardless of cause, harvest of chinook salmon was reduced 90 percent by 1992 (Figure 70) . With chinook salmon catch down, angling effort also dropped and harvest of all trout and salmon declined to a total catch of around 2 .7 million kilograms (6 million pounds) ; approximately equal to historic indigenous lake trout production (Figure 70). Of the stocked salmonines, lake trout were assumed to be the species with the greatest potential for self-sustainability, because they were indigenous to the lake (Wells and McLain 1973) . Lake trout failure to establish self-sustaining reproduction is disconcerting . Scientists have not been able to conclusively identify the problem . Hypotheses for explaining failure of lake trout reproduction include incorrect stocking locations or procedures, failure to control overfishing, bio-accumulation of chemical contaminants, alewife predation on eggs and larvae, spawning habitat degradation, and/or use of the wrong genetic strains of lake trout . Prior to 1985, changes in stocking approaches and fishing effort confounded the problem, making it impossible to isolate the reason for reproductive failure . However, a comprehensive plan for lakewide rehabilitation was developed and approved by the Lake Michigan agencies in 1985 (Great Lakes Fishery Commission 1985) . The rehabilitation plan had a long-term goal of establishing a self-sustaining population capable of yielding 1 .1 million kilograms (2 .5 million pounds) annually, and emphasized stocking lake trout in the best spawning habitats and controlling fishing mortality . Especially large plants were made in two offshore refuges beginning in 1986 (Figure 72) . Some momentum in implementing the new plan, which called for stocking a mixture of lake trout strains, was lost because of mortality in the supplying hatcheries . A full evaluation of the 1985 lake trout rehabilitation plan will not be completed until the late 1990s. Nearshore fish community Nearshore fish communities were generally considered more diverse and productive than the offshore communities due to warmer temperatures and higher nutrient levels . Important inshore fish species and their ecological classifications based on feeding strategy are : lake sturgeon, benthivore ; lake whitefish, benthivore ; emerald shiner, planktivore (Hartman et al. 1992); suckers, benthivores ; yellow perch, omnivore ; and walleye, piscivore . Of all the inshore areas of the lake, the most productive fish communities probably existed in southern Green Bay, other shallow embayments, and in estuaries . Green Bay was also an important spawning ground and nursery area for lake herring, in what otherwise is classified as a percid community (Ryder and Kerr 1990) with walleye, yellow perch, suckers, and northern pike being key species .

121

_ake

Michigan '

Figure 72 . Map of Lake Michigan illustrating lake trout rehabilitation zones (Lake Michigan Technical Committee).

Yellow perch were abundant in nearly all the shallow areas of Lake Michigan, and were important to both sport and commercial fisheries . An abrupt decline occurred in the early and middle 1960s, progressing from north to south, so that by the late 1960s, substantial populations existed only in the extreme southeastern portion of Green Bay- (Wells and McLain 1973) . The reason for the decline was greatly diminished reproduction, which in turn appears to have been associated with concurrent build-up of alewife . Perch stocks remained low until the 1980s when the alewife population declined. Average total harvest of perch in 1985-1987 was 1 .8 million kilograms (3 .9 million pounds), but historic commercial yield through 1956, before alewife became prominent, was only half that amount (Figure 68). Poor larval recruitment has led to a series of weak year classes (1990-1994) in the southern basin . A dramatic decline in the population has occurred and alewife predation is again a suspected factor. Lake whitefish was the mainstay of the early commercial fishery in Lake Michigan (Wells and McLain 1973) . It was easily taken in large quantities even in shore seines . Early accounts indicate a substantial decline in the abundance of lake whitefish well before commercial production figures were available . Lake whitefish harvest averaged between 0.5 and 1.4 million kilograms (1 and 3 million pounds) from the early 1900s through the 1950s, before their collapse during the period of alewife increase (Figure 68) . Since the mid 1960s, however, lake whitefish stocks and harvest have recovered . Since 1981, the annual harvest has been steady and has not dropped below 2 .3 million kilograms (5 million pounds) .

122

Lake Michigan.

Causes of Changes in Lake Michigan Fishery Resources and Management Strategies Causes of changes in Lake Michigan fishery resources Combined effects of fishing, habitat destruction, and introduced species have severely disrupted the indigenous fish community (Smith 1972) . Before the 1950s these losses were incremental and did not change fundamental food web linkages, except for fishes dependent upon tributaries for spawning such as brook trout, various minnows, and red horse suckers . Of 12 introduced fishes (Bailey and Smith 1981), the unintentional introduction of sea lamprey, first observed in 1936, caused the most disruption because it contributed to the collapse of top predator populations (lake trout and burbot) by the late 1940s (Wells and McLain 1973) . Elimination of top predators allowed the alewife, which invaded in 1949, to proliferate and further disrupt the indigenous food webs (Smith 1970). Alewife are planktivores and their overabundance probably resulted in depression of plankton populations for other planktivores and themselves . Their grazing on pelagic larval fish is believed to have resulted in extinctions of three species of deepwater coregonids and suppression of emerald shiner, lake herring, yellow perch, and deepwater sculpin (Crowder 1980 ; Eck and Wells 1987) . Alewife also have been recently implicated as a possible factor inhibiting success of lake trout reproduction, as they have been observed eating lake trout fry (Krueger et al. 1995). Burbot and spoonhead sculpin may also have been depressed by alewife . By the 1960s, the lake was dominated by alewife and to a lesser extent rainbow smelt, another introduced species . By then, the indigenous fish community was severely disrupted and important commercial and angler fisheries had collapsed. Stocked salmonines were likely responsible for much of the reduction observed in the overabundant alewife population during the 1970s . Alewife were further reduced by low recruitment during the early 1980s, probably due to unfavorable weather conditions (Eck and Wells 1987) . Which of these factors, predation or weather, had the biggest effect on reducing alewife abundance is uncertain, but alewife populations declined . Jude and Tesar (1985) reported that alewife declined 86 percent between 1980-1982, and Eck and Wells (1987) reported a six-fold decline during 19811983 . The alewife decline appeared to have a number of desirable effects . Increases in abundance were observed for several indigenous species, including deepwater coregonids (now reduced to a single species), the bloater, yellow perch, and deepwater sculpin . By 1982, bloaters were more abundant than alewife (Eck and Wells 1987) -- a dramatic change in the Lake Michigan fish community . Despite the declines in alewife and improvements in availability of alternative prey during this period, the salmonines continued to rely primarily on alewife as prey (Figure 73 ; Jude et al. 1987). Progress in fish community rehabilitation began in 1960, with extension of the sea lamprey control program to Lake Michigan . Smith and Tibbles (1980) provide a thorough history of the sea lamprey invasion of the upper Great Lakes and of control measure implementation . Suppression of sea lamprey was a necessary prelude to re-establishment of piscivores and remains essential . Lake trout planting began in 1965 and coho salmon and chinook salmon were introduced from the Pacific Northwest in 1966 and 1967, respectively . Brown trout and rainbow trout were also extensively stocked (Figure 71) . Of the five major salmonines planted, only lake trout was released with the main objective being to re-establish reproducing populations . The main objective for stocking the others was to provide put-grow-take angling opportunities and to control alewife (Tody and Tanner 1966) . Sporadic evidence of possible lake trout reproduction has been reported over the years, but sustainable reproduction has not developed . A brief increase in recoveries of unclipped and possibly naturally reproduced lake trout occurred in Grand Traverse Bay in the early 1980s, but recoveries of unclipped fish declined again by the mid-1980s (Rybicki 1983) . Natural reproduction of brown trout has also been very limited (Lake Michigan Task Force 1990), but significant reproduction has been established for rainbow trout (Seelbach 1986 ; Carl 1983), chinook salmon (Carl 1982, 1983 ; Seelbach 1985), and coho salmon (Carl 1982 ; Seelbach 1985 ; Patriarche 1980) . In association with salmonine stocking programs, lake whitefish made a spectacular recovery in northern waters (Figure 68).

123 Ike

100

Michllgan `t

misc . fish ® Stickleback I l Sculpt')

80

Chubs ElSmelt Alewife

60

40

20

0 Figure 73 . Percent weight composition of diet items for lake trout, coho salmon, chinook salmon, brown trout and rainbow trout in Wisconsin waters for the years 1990 and 1991 combined (Wisconsin Department of Natural Resources).

The collapse of the chinook fishery in the late 1980s raises questions about the sustainability of hatchery-based salmonine fisheries as we have known them since establishment of alewife in Lake Michigan . Recent problems with low egg viability of coho salmon and steelhead eggs in Lake Michigan hatcheries supports concern for the sustainability of the trout and salmon fisheries . As many as 80 percent of coho salmon fry have died at some hatcheries . Management agencies are concerned whether the spawning runs of coho salmon will be large enough to provide enough eggs to compensate for the poor egg survival . As a result, they have recently agreed to reduce the daily limit lakewide . Lakewide predation has maintained alewife at a comparatively low level, even with drastically reduced chinook salmon abundance . The increase of self sustaining stocks of trout, salmon, burbot, bloater, and perch may result in diminished ability to create the desired fish community through stocking . Future fish management in Lake Michigan, will need to consider the fish community as a whole, not focus on single species management. Lake Michigan's fish community will also continue to change as nonindigenous species continue to invade and exert their influence throughout the lake . Yellow perch recruitment has been absent since 1989 in the southern basin of Lake Michigan, even though fry have been found shortly after hatching . Possible causes include interactions with nonindigenous species such as alewife, zebra mussel and spiny water flea, as well as environmental factors . The spiny water flea, a large cladoceran that preys on small-bodied zooplankton, became prominent in 1986 in Lake Michigan. It entered the Great Lakes in ballast water discharged from ocean-going ships (Lehman 1991) . The spiny water flea may compete with larval bloater for zooplankton and disrupt the pelagic food web (Lehman 1991) . Other invaders from ballast water that may perturb the fish community are the zebra mussel ; the ruffe, a perch-like fish that is presently confined to western Lake Superior (Pratt et al. 1992) ; and the round goby, one of two introduced gobies discovered in the St . Clair River in 1990-1991 (Jude et al. 1992) .

124

Lake'Michigan

Management strategies in Lake Michigan The overall goals for the restoration of ecosystem integrity to the Great Lakes have been established primarily through the Great Lakes Water Quality Agreement of 1978, as amended in 1987, and the Strategic Plan for Management of Great Lakes Fisheries (Great Lakes Fishery Commission 1980) . The water quality agreement contains an important goal relating to pollution control which must be attained before healthy fish and wildlife communities can be realized: to restore and maintain the chemical, physical, and biological integrity of the waters of the Great Lakes Basin Ecosystem. Fish Community Objectives for Lake Michigan presented seven statements summarizing actions needed to attain the desired fish community: Establish a diverse salmonine community capable of sustaining an annual harvest of 6 to 15 million pounds, of which 20 to 25 percent is lake trout . Establish self-sustaining lake trout populations. Maintain a diversity of planktivore (prey) species at population levels matched to primary production (autotrophic production) and to predator demands . Expectations are for a lakewide planktivore biomass of 1 .2 to 1.7 billion pounds. Maintain self-sustaining stocks of yellow perch, walleye, smallmouth bass, esocids, catfish, and panfish . Expected annual yields should be 2 to 4 million pounds for yellow perch and 200,000 to 400,000 pounds for walleye. Maintain self-sustaining stocks of lake whitefish, round whitefish, sturgeon, suckers, carp, and burbot. The expected annual yield of lake whitefish should be 4 to 6 million pounds. Suppress sea lamprey to allow the achievement of other fish community objectives. Protect and sustain a diverse community of native fishes, including other species not specifically mentioned earlier (e.g. cyprinids, gar, bowfin, brook trout, and sculpins) . These species contribute to the biological integrity of the fish community and should be recognized and protected for their ecological significance, and cultural and economic values. Protect and enhance fish habitat and rehabilitate degraded habitats . Achieve no net loss of the productive capacity of habitat supporting Lake Michigan's fish communities. High priority should be given to the restoration and enhancement of historic riverine spawning and nursery areas for migratory species . Pursue the reduction and elimination of contaminants where possible to enhance fish survival rates and allow for the promotion of human consumption of safe fish.

125

Lake Superior .

ake Superior Historic and Current Status of Fishery Resources Due to the its great size and depth, many of the biological resources of Lake Superior have been more difficult to study than in the other Great Lakes . Until recently, studies of phytoplankton, zooplankton, and invertebrates have been limited in scope and significance (Matheson and Munawar 1978) . Life history studies of important commercial fishes had been done by the 1950s, but did not address the unforeseen interactions among indigenous and nonindigenous species that transformed the fisheries in later years . Appendix II lists species composing the Lake Superior fish community (past and present), and current status of stocks being monitored. Since the early 1970s, fisheries studies on Lake Superior have been well-coordinated with the formation of the Great Lakes Fishery Commission . Coordination, however, is difficult because management responsibilities are fragmented among several U .S . and Canadian jurisdictions . Under the broad guidance of the Strategic Plan for the Management of Great Lakes Fisheries, the agencies of the Lake Superior Technical Committee have made much progress in understanding Lake Superior's fishery ecosystem, in restoring habitats and species, and in joint inter-agency planning (Hansen 1994) The summary of the history and status of Lake Superior's fish community provided here is not a comprehensive review . For more complete treatments, the reader is referred to Lawrie and Rahrer (1973), Lawrie (1978), MacCallum and Selgeby (1987), and Hansen (1990, 1994). A total of 94 fish species from 24 families are known from Lake Superior and its tributaries (Appendix II) . Seventy-six of the species are indigenous (defined as occurring in 1885, or having entered the system without human influence). Twenty-three of the species are known only from tributary streams, so 71 fish species have inhabited the lake during the past century . Two tributary species have been extirpated from the watershed. For purposes of description, Lake Superior can be divided into depth zones, each of which is characterized by a unique fish community . There is much interchange of material and energy among the zones due to currents, upwellings, and movements of fish and other organisms. Offshore fish community The offshore zone is defined as waters deeper than 73 meters (240 feet) and comprises about 80 percent of Lake Superior or 6.4 million hectares (16 million acres) . This zone is occupied by pelagic fishes in the mid- to upper-water column, and bottom-dwelling fishes in the demersal habitat, where darkness is constant and temperatures are stable at 3 .9 °C (39 °F) . The offshore fish community, consists of 13 species from eight families. A simple food chain was responsible for most historical fish production in Lake Superior : primary production by phytoplankton in the open lake supported zooplankton, which was eaten by lake herring, which are pelagic in offshore waters . Lake herring made up about half of the historical fishery yield . They were eaten by lake trout, the primary predator and the species of highest commercial value in the fishery, until their decline in the 1950s . Historically some lake trout suspended over deep water during the growing season to prey on lake herring. Horizontal and vertical movements of invertebrates and fish are important in the energy flow of the Lake Superior fishery ecosystem . Most primary production occurs in the offshore zone because of its huge surface area, and despite its low fertility and phytoplankton density . Zooplankton and the opossum shrimp Mysis relicta move vertically in response to light, and fish of the offshore zone, such as lake herring and lake trout, follow these movements . The rain

126

of organic particles from upper water layers nourishes bottom-feeding fish, such as deepwater coregonids and sculpins. Through seasonal horizontal movement, lake herring and lake trout transfer tons of biomass to inshore areas in the form of sex products, thus benefitting inshore bottom feeders that feed on eggs deposited on the bottom . These energy flow patterns were disrupted when lake trout and lake herring stocks were depleted. Lake trout were widely distributed in Lake Superior, and formed many local discrete populations, varying in morphology, behavior, and life history (Goodier 1981) . These include the "lean" lake trout, the "fat" lake trout (or siscowet), " halfbreeds", and "bumpers" (also known as "bankers" or "paperbellies") . Other variants historically pursued by fisheries are now probably extinct. Lake trout stocks supported large commercial fisheries (Figure 74), with relatively stable harvests of about 1 .8 million

12

Lake trout Chubs Lakeherrin7 c

YEAR

Figure 74 . Annual commercial harvest of offshore fishes from Lake Superior, 1885-1990 . Offshore fishes are those typically inhabiting waters deeper than 73 m (240 ft) . Species include lake trout, chubs, and lake herring (data from Baldwin et al . 1979 and Great Lakes Fishery Commission). kilograms (4 million pounds) per year from 1920 to 1950 (Lawrie and Rahrer 1972, 1973) . Abundance declined sharply during the 1950s because of commercial fishing and predation by the sea lamprey (Pycha and King 1975), which had colonized Lake Superior during the 1940s and 1950s (Smith and Tibbles 1980) . Harvest of lake trout declined more that 90 percent from 1953 to 1962, when management agencies severely curtailed commercial fishing for lake trout (Pycha and King 1975) . Curtailment of commercial fishing for lake trout (approximately in 1962) was associated with the effective chemical treatments to suppress sea lamprey that began in 1958 in Lake Superior tributaries . By 1961, these treatments had reduced sea lamprey numbers by 85 percent (Smith et al. 1974). By the time sea lamprey control became effective, lake trout stocks had been extirpated or reduced to remnant populations. Stocking of hatchery lake trout caused abundance to increase rapidly in parts of the lake in the 1960s and 1970s



127

(Pycha and King 1975) . Stocking of hatchery lake trout averaged 2 .5 million annually between 1970 and 1983, and 3 .3 million between 1984 and 1992 (Ebener 1989; Hansen 1994) . However, survival of stocked lake trout declined significantly in the 1980s (Hansen et al. 1994), probably due to competition or predation experienced soon after stocking . Remnant wild stocks have recovered slowly but steadily since 1961 (Swanson and Swedberg 1980; Curtis 1990; Hansen 1990) . Now the maintenance of lake trout stocks in Lake Superior depends mostly on natural reproduction, rather than stocking (Hansen et al. 1994) . Reproduction has increased markedly since 1970, but the increase has slowed since the mid-1980s (Hansen et al., in press), and numbers of wild lake trout have decreased in some zones, probably due to commercial fishing (Peck and Schorfhaar 1991) . According to Hansen et al. (1994), "Lake trout restoration may now depend on prudent management of naturally reproducing stocks, through reduction of fishing effort and sea lamprey abundance ."

Ashland Fishery Resources Office photo

Lake herring stocks declined drastically in the 1950s and 1960s (Figure 74), after lake trout stocks had crashed . From 1916 to 1940, a historical reference period used as a benchmark by Lake Superior fishery managers, lake herring made up 64 percent of the total commercial landings (Baldwin et al. 1979) . However, by the 1970s, lake herring were scarce in much of Lake Superior . The decline began in Minnesota, perhaps as early as 1941, when harvest first fell below that State's historical average of 2 .7 million kilograms (5 .9 million pounds) . Similarly, landings dropped below the historical Wisconsin average in 1963 of 0.7 million kilograms (1 .5 million pounds) and in Michigan in 1970 of 0 .7 million kilograms (1 .5 million pounds) . In Ontario, commercial landings remained near the historical average of 0 .9 million kilograms (2 .0 million pounds) until 1988, when harvest fell to 0 .4 million kilograms (0 .9 million pounds), due to a sharp decline in the important Black Bay stock . The lake herring's niche of pelagic grazer was virtually vacant for about 30 years . In the other Great Lakes, this niche had been filled by the nonindigenous immigrant alewife and rainbow smelt, but low temperatures limited alewife abundance to a very low level in Lake Superior (Bronte et al 1991).

Since about 1983, however, lake herring biomass has increased more than tenfold, though not in all parts of the lake (Hansen 1994) . Fishery managers view the strong recovery of lake herring as one of the most important and positive occurrences in Lake Superior in recent decades. Lake Superior supports three species of deepwater coregonids, close relatives of the lake herring also known as "chubs". Some literature (e .g . Lawrie 1978) lists additional species in Lake Superior, but specimens of bluefin, blackfin, or shortnose ciscoes have been re-classified as shortjaw ciscoes (Becker 1983) . The chubs are less pelagic than lake herring, and generally feed near the bottom . They are important forage for lake trout and burbot. Commercial harvest of chubs (Figure 74) has never been separated by species, because they are so similar in appearance . However, shortjaw cisco made up about 90 percent of commercial harvest in the 1920s (Koelz 1929) . After 1950 the commercial harvest shifted to the smaller kiyi and bloater (hoyi) as the shortjaw declined (Lawrie 1978). Currently the shortjaw cisco is a Category 2 species under consideration for Federal endangered or threatened status by the Service. Since the 1970s, commercial harvest and abundance of chubs have declined markedly (MacCallum and Selgeby 1987; Hansen 1994) . Increasing predator stocks, especially the siscowet lake trout (Hansen 1994), may be exerting heavy predation on chub populations .

128

LaK Superior

Introduced species of Pacific salmon have been important in the Lake Superior fish community since the late 1960s. Pink salmon were inadvertently introduced in 1956, and coho salmon and chinook salmon have been stocked for sport fishing since 1967 . The pink salmon is a relatively small fish that feeds mostly on plankton . It reproduced in Lake Superior and became quite abundant in the late 1970s, but has since declined (Bagdovitz et al. 1986) . However, conclusions of a general decline in pink salmon may be premature (Kelso and Noltie 1990). Coho and chinook salmon range widely in Lake Superior, becoming pelagic as adults . They spawn in tributary streams, and have both established self-sustaining populations . Coho salmon likely reproduce in all Lake Superior streams that have suitable spawning substrate and are accessible during the spawning period (Hansen 1994), but little reproduction occurs in Minnesota streams . Coho salmon spawning runs are highly variable from year to year, resulting in high variation in sport harvest . Chinook salmon have been observed spawning in numerous streams in the U .S. and in most large rivers in Canada (Hansen 1994), though spawning runs have declined in recent years . Recent studies of marked stocked fish revealed that most coho and chinook salmon in Lake Superior are produced through natural reproduction . Both species are known to be infected with bacterial kidney disease, which may threaten their natural populations (Hansen 1994). Inshore fish community The inshore habitat of 9-73 meters (30-240 feet) depth makes up 18 percent of Lake Superior, or about 1 .4 million hectares (3 .6 million acres) . This zone is very narrow in some parts of the lake, especially the Minnesota north shore, the northeast shore in Ontario, and portions of Michigan waters . The most productive portions of Lake Superior have a relatively broad inshore zone, such as southwestern Lake Superior (Apostle Islands and Chequamegon Bay), the three large bays, Nipigon, Black, and Thunder Bays in Canada, and Whitefish Bay in the southeast. The inshore fish community is dominated by 14 species, of which half also occur in the offshore zone . Seven families are represented in this fish community . The inshore habitat is occupied by important bottom-feeders, including lake whitefish and longnose sucker. Several fishes of the offshore and nearshore zones use the inshore seasonally for spawning or feeding . For example, spawning lake herring congregate over reefs and flats in the inshore area, depositing eggs that are fed upon by inshore fishes . Walleye and other nearshore fishes move into water deeper than 9 meters (30 feet) in warm summers when temperatures are favorable. Lake whitefish have been and continue to be an important Lake Superior commercial species (Figure 75) . The fishery has passed through several episodes, characterized by different trends in harvest (Lawrie 1978) . Harvest increased since 1961, the year sea lamprey control became effective, until about 1990, and in recent years has been at historically high levels (Hansen 1994) . Most of the increase resulted from fishing-up of previously unfished or lightly fished stocks; however, heavily fished stocks have also maintained or increased their abundance (Hansen 1994) . Recent commercial harvest has exceeded 1 .1 million kilograms (2 .5 million pounds) per year. Adult rainbow smelt occupy the inshore, and since the 1950s been the major food of salmonid predators (Dryer et al. 1965; Conner et al. 1993) . After lake herring stocks collapsed, the lean lake trout utilized inshore habitat to prey on rainbow smelt . Rainbow smelt abundance remained high in inshore waters, especially in western Lake Superior, until 1978-1981, when biomass declined by 90 percent due to high mortality of rainbow smelt older than 2 years (Selgeby 1985) . Abundance has varied considerably since 1981, as rainbow smelt have produced strong year classes, but have continued to undergo high levels of mortality (Hansen 1994) .

129

rake Superior

1885

1905

1985

1925 YEAR

Figure 75 . Annual commercial harvest of select inshore fishes from Lake Superior, 1885-1990. Inshore fishes are those typically inhabiting waters between 9 and 73 m (30-240 ft) in depth. Species include burbot, suckers, rainbow smelt, round whitefish and lake whitefish (data from Baldwin et al. 1979 and Great Lakes Fishery Commission),

Nearshore fish communities The nearshore habitat less than 9 meters (30 feet) in depth makes up only 2 percent of Lake Superior, or about 160,000 hectare (400,000 acres) . Its importance is much greater than its proportion of the lake, being the most productive habitat, with the most diverse biota . Fifty-two fish species of 19 families are recorded from the nearshore habitat . Nine of the species are nonindigenous, including five that were probably introduced accidentally via ship ballast water. The nearshore should be further subdivided into the open nearshore and coolwater bays . The open nearshore is a coldwater habitat subject to strong currents and wind-generated turbulence . This habitat supports a less diverse fish community, with coldwater species that prefer temperatures of 10-15 .5 °C (50-60 °F) . The fish community of coolwater bays resembles that of many northern inland lakes, with species that prefer temperatures of 18 .3-23.9 °C (65-75 ° F) during the growing season. Rainbow trout and brown trout are nonindigenous to Lake Superior, but are long-time residents that have reproduced in the lake since about 1900 . Both species occupy open nearshore habitat while in the lake, and spawn in tributary streams . They are popular sport fish in lake or stream, and continue to be stocked for sport fishing. Lake sturgeon has been recommended for official threatened status (Williams et al. 1989), and is a Category 2 species under consideration for Federal listing by the Service . The sturgeon was once abundant in estuaries and nearshore waters, but was nearly extirpated from Lake Superior (Lawrie 1978) . A commercial harvest of 101,605 kilograms (224,000 pounds) was recorded in 1885, and fell steadily thereafter (Lawrie and Rahrer 1973) due to overfishing and

130

ake Superior`

habitat destruction (Figure 76) . Lake sturgeon first mature and spawn at an age of over 20 years, so many years of protection are required to restore stocks . The extirpated stock in the St . Louis River of Minnesota and Wisconsin is being restored through stocking. Abundance is increasing steadily, but the fish have not yet reached the age of sexual maturity . In the U .S ., the Bad River in Wisconsin and the Sturgeon River in Michigan are the only two remaining tributaries supporting naturally reproducing stocks .

YEAR

Figure 76 . Annual commercial harvest of nearshore fishes from Lake Superior, 1885-1990. Nearshore fishes are those typically inhabiting waters less than 9 m (30 ft) in depth . Species include sauger, walleye, northern pike, and lake sturgeon . (data from Baldwin at al. 1979 and Great Lakes Fishery Commission)

"Coaster" brook trout were once the only trout of nearshore waters, before the introduction of rainbow and brown trout. Coaster brook trout were abundant in the catches of early anglers . Robert Barnwell Roosevelt (1865) wrote: "The finest trout fishing in the world is to be obtained at Lake Superior; . .. nowhere is to be found the same abundance of trout, averaging above two pounds, and wonderfully game and vigorous... . The entire rocky shore of the lake, along both coasts, is one extensive fishing grounds, where the skillful angler can at any point find delightful sport; the innumerable tributaries, large and small, of the British or American territory, unless shut out by precipitous falls, are crowded with myriads of the speckled beauties; and the rapids at the outlet furnish trout of the largest size, .. ."

Ashland Fishery Resources Office photo

131

Laica-Superior

Roosevelt also warned that coaster populations were declining, as early as the mid-1800s . Abundance of coaster brook trout fell to very low levels due to overfishing, loss of suitable habitat, and competition with introduced trout and salmon (Hansen 1994) . The largest existing population spawns in the Nipigon River, Ontario . Remnant populations also exist in some other Ontario and Michigan streams (Hansen 1994). Walleye are locally important in the nearshore waters of Lake Superior, especially in coolwater bays . Walleye in Lake Superior tend to be slow-growing and long-lived (Schram et al. 1992) . Most walleye stocks in Lake Superior declined due to fishing (Schram et al. 1991), though habitat degradation has also been a significant problem (Ryder 1968) . Walleye have partially recovered with the assistance of fishing regulations, habitat restoration, and stocking (Hansen 1994). Ashland Fishery Resources office photo

Tributary fish communities Lake Superior has a small, steep watershed, so tributary streams are relatively short and numerous . Lawrie and Rahrer (1973) counted 1,525 tributary streams, of which 840 are in the United States . Many of these streams are intermittent, but all convey runoff to the lake at some time each year. Stream habitat is diverse, due to the diverse geological formations that make up the watershed . Many high-gradient coldwater streams support low-diversity fish communities of trout, salmon, dace, and sculpins, while a lesser number of low gradient streams support cool and warmwater fish communities . Twenty-three species of eight families are known only from tributary streams . All but two of these species are indigenous, and 13 of the 23 are members of the minnow family, Cyprinidae . However, many fishes of Lake Superior enter tributaries to spawn, or are found in both streams and nearshore lake waters . Two tributary species of limited distribution, the Arctic grayling and paddlefish, have been extirpated from the watershed. Moore and Braem (1965) recorded fish collected coincident to sea lamprey investigations on 175 tributaries . They found 71 species of 20 families . Among the most widely distributed were sea lamprey, rainbow trout, brook trout, rainbow smelt, longnose dace, blacknose dace, common shiner, creek chub, white sucker, longnose sucker, mottled sculpin, and burbot.

Causes of Changes in the Lake Superior Fishery Resources and Management Strategies Causes of changes in Lake Superior fishery resources The Lake Superior fish community has been subjected to a series of stresses that affected it temporarily or permanently. During the logging era of the late 19th and early 20th centuries, "shallow-water benthic environments were



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Lake:Superior:

ruinously affected by the deposition of sawdust and other woody, allochthonous materials" (Lawrie 1978) . Sturgeon, whitefish, and some other river and estuarine stocks were lost or adversely affected. Later in the 20th century, widespread low-level contamination of fishes by organic compounds and heavy metals has been measured . Contaminants entered from point sources, and from aerial deposition . Adverse effects on fish have not been observed in Lake Superior, but cannot be ruled out . Several of the contaminants, notably mercury, dioxin and PCBs, are known to cause chronic and acute human health effects at sufficiently high levels . Excessive levels of mercury and PCBs have caused State health agencies to issue advisories, warning people to limit consumption of lake trout, siscowet, walleye, chinook salmon, northern pike, white sucker, lake whitefish, and yellow perch (Busiahn 1990) . Point sources of contaminants still exist ; the Copper Range Company in Ontonagon County, Michigan, about 8 kilometers (5 miles) from Lake Superior, continues aerial discharges of large quantities of mercury, lead, and copper, as well as contaminated sediments . Other continuing sources of pollution in the Lake Superior watershed include the Murphy Oil Company in Superior, Wisconsin, mining activity in Minnesota, and pulp- and paper-mill effluent in Ontario (Hansen 1994) A third stress on the fish community was the fishery itself . Uncontrolled fishing by the "aggressive and enterprising commercial fisheries" produced the destabilizing effects of intense size-selective predation (Lawrie 1978) . The fishery was probably too intensive to persist for long at that level, but the invasion of the sea lamprey doomed the fishery. According to Waters (1987) : _ "[I]t is now generally accepted that, by 1950, the fish community of Lake Superior had been brought to the sharp edge of a catastrophe, ready to give way at any time . A system of instability, lacking the checks and balances that had evolved over millennia of natural evolution, had gradually crept up over a mere 100 years, unseen in the euphoria of abundance. The sea lamprey was the factor that caused the sharp edge to crumble, and the biological system collapsed." Sea lamprey were first noted in Lake Superior in 1946, and by the late 1950s had nearly destroyed the lake trout population. A successful search for a control method culminated in the treatment of sea lamprey spawning streams with the toxicant TFM starting in 1958 . The ensuing history of the sea lamprey has been extensively documented (e.g. Smith et al. 1974 ; Smith and Tibbles 1980). Lake herring declined dramatically in the 1950s and 1960s . Researchers have debated the cause of the lake herring declines . Anderson and Smith (1971) argued that increasing populations of rainbow smelt and bloater influenced lake herring through competition during larval stages . Rainbow smelt were first recorded in Lake Superior in 1930 and became abundant during the 1950s . However, Selgeby et al. (1994) found competition between larval rainbow smelt and lake herring to be "almost nonexistent" . Anderson and Smith (1971) argued that overfishing was not correlated with the decline of lake herring, but Selgeby (1982) showed that lake herring stocks in the Apostle Islands of Wisconsin were sequentially "fished-up" during the fall while segregated into discrete spawning stocks . Peck et al. (1974) reached the same conclusion when they studied the Michigan commercial fishery . Thus commercial harvest and catch rates remained deceptively high as the fishery depleted discrete stocks and then moved on to yet productive ones . Neither Anderson and Smith (1971) nor Selgeby et al. (1978) found predation on young lake herring to be a major factor in suppressing lake herring stocks. Lake herring abundance in U.S. waters has increased sharply since 1981, though the recovery has not occurred in all areas . A demonstrated preference by most trout and salmon for rainbow smelt may have allowed the strong resurgence of lake herring . Since the 1960s, rainbow smelt have dominated the diets of inshore lake trout and other salmonid predators (Dryer et al. 1965; Conner et al. 1993) . Rainbow smelt and coregonines (e .g. lake herring and chubs) have not been consumed in proportion to their abundance ; most salmonine predators consistently selected rainbow smelt during the 1980s, though coregonine biomass was more than double that of rainbow smelt (Conner et al. 1993). Only offshore lake trout diets were dominated by coregonines . More recently, increased occurrence of coregonines in

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Lake Superior

the diets of lake trout has been observed (Gallinat 1993), and wild lake trout have been found to have a more diverse diet, consuming fewer rainbow smelt than hatchery-produced fish (Hansen 1994). Stocking of fish has caused major changes in the fish community . Angling opportunities have been diversified by introduced trout and salmon species, but ecosystem effects have been unpredictable and difficult to monitor. According to Waters (1987): "At one time or another, almost every salmon, Atlantic and Pacific, was tried in the Great Lakes, but all failed. We think today that the reason for these early failures was that the indigenous lake trout-whitefish-lake herring-chub system was so well established and stable that nonindigenous species could not penetrate it . But that indigenous stability was lost. .. . New predators now successfully share the position of top predators with the lake trout and burbot; new forage species replace the old as food for the predators . The system is more complex now, and more difficult to understand, for the newcomers have different environmental requirements with respect to ... water depth, temperature, food, and spawning needs." Several introduced predator species reproduce naturally, but stocking continues . The impact of stocked predators on the forage base, and ability of the forage base to sustain projected stocking levels are poorly known (Busiahn 1985, Negus 1992) . In recent years, rainbow smelt have been the primary prey of most trout and salmon species (Conner et al. 1993), and rainbow smelt populations have experienced a sharp decline and continuing high mortality (Hansen 1994) . Lake trout growth rates were lower in the 1970s, when rainbow smelt dominated their diets, than in the 1950s, when lake herring were the major food (Busiahn 1985) . Chinook salmon consume large amounts of food in a short time, and could be formidable competitors if the supply of forage fish is limited (Negus 1992) . Conner et al. (1993) found that coho salmon consume large amounts of rainbow smelt, but selected rainbow smelt of a smaller size than did lake trout or chinook salmon . Diets of coho salmon also included large numbers of terrestrial and aquatic insects. Long-term stability in the fish community will likely depend on the coregonine forage base, especially lake herring. The nearshore fish community has been most affected by human land use activities in the Lake Superior basin. Relationships between land use and the fish community can be direct and obvious, or subtle and difficult to discern . They can be of a positive nature, though most are negative . Fifteen uses of land in the Lake Superior basin were identified, and placed into four categories . Thirteen effects on the fish community were identified, and grouped into eight categories . A matrix of land uses and effects was constructed to examine the interactions (Tables 9-11) . The tables indicate interactions among land uses and nearshore fish community effects, but do not describe those effects . Nevertheless, they indicate some interesting patterns. For example, trapping of forbearers, a major industry in the Lake Superior country in the early 1800s, may have had several effects on the fish community, most probably positive (Table 9) . The depletion of beaver would have resulted in the eventual breakdown of dams that obstructed streams . As a result, many small streams may have been opened to migratory fish passage . Removal of dams may also have reduced other negative effects such as widening and warming of streams, and siltation of spawning areas . The removal of otters would have reduced a source of mortality of nearshore and stream-dwelling fishes . On the other hand, fur companies were the first major commercial exploiters of fish for market, and began the ruinous "fishing-up" of Lake Superior's valuable fish stocks (Waters 1987). The negative effects of logging (Table 9) were pervasive, though mostly indirect . The removal of the forest canopy opened streams to direct sunlight, and exposed soils to erosion . Fires that followed the liquidation of the forest led to further erosion and sedimentation, which buried productive riffle areas with sand . Stream flows became more variable with higher water temperatures . The transportation of logs in log drives caused short-term devastation of stream habitat . Perhaps the only positive thing to be said about logging was that runoff from the logged-out, burned-up landscape may have temporarily increased fertility of receiving waters through increased nutrient levels .

134

Table 9 . Effects of extractive land uses on the nearshore fish community of Lake Superior (X = effect present) .

Extractive Land Use

Subsistence

Trapping

Logging

Mining

x

x

x

Agriculture

Habitat Destruction Filling Damning

x

Habitat Alteration Spawning substrate

x

x

Stream flows

x

x

x

Temperature

x

x

x

x

x

x

Species Introductions Nutrification Secondary Effects Food Chain

x

Tainting Direct Mortality

x

x

Fishery Harvest

x

x

x

x

x

x

x

x

Low Level Stressors Chemical Biological

Table 10 . Effects of industrial land uses on the nearshore fish community of Lake Superior (X = effect present) .

Industrial Land Uses Sawmills

PulplPaper

Oil/Chemical

Power Plants

Hydropower

Habitat Destruction Filling Damming

x

Habitat Alteration Spawning substrate

x

x

Stream flows

x

Temperature

x

x

x

x

x

x

x

Species Introductions Nutrification Secondary Effects Food chain

x

Tainting

x

Direct Mortality

x

Fishery Harvest Low Level Stressors Chemical Biological

x

x

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Lake Superior

Table 11 . Effects of transportation and social land uses on the nearshore fish community of Lake Superior (X = effect present) .

Transportation and Social Land Uses Highways

Marine

x

x

x

x

x

x

Railroad

Urbanization

Recreation

Habitat Destruction Filling Damning Habitat Alteration Spew ning substrate Stream flow s

x

Temperature

x

Species Introductions

x

x

Petrification

x x

x

x

x

Secondary Effects Food chain Tainting Direct Mortality Fishery Harvest

x

x

Low Level Stress ors Chemical

x

x

Biological

Hydropower dams were built on several rivers flowing into Lake Superior (Table 10) . Dams may block migration and reduce the productive capacity of these systems for anadromous fishes . In the U .S ., these include the St . Louis River in Minnesota ; the Iron, White and Montreal Rivers in Wisconsin ; and the Autrain, Dead, Ontonagon and Sturgeon Rivers in Michigan . In Canada, the Nipigon River and others have been similarly affected . Several of the dams were constructed at high-gradient sites, where fish migration was naturally blocked, in which case most impacts were experienced through alteration of downstream flow . Manipulation of flow to meet peak electrical demand has often left fish stranded and fish eggs and fry desiccated. Examples include coaster brook trout in the Nipigon River, Ontario; walleye in the St . Louis River, and lake sturgeon in the Sturgeon River, Michigan. Most effects of land use are reversible, but irreversible effects have the greatest long-term impact . The introduction of non-indigenous species (Table 11) through deliberate planting, accidental planting, ship ballast water, or opening of waterways to colonization produces effects that will likely never be reversed. Management strategies in Lake Superior Agencies responsible for managing Lake Superior fisheries agreed on the desired state of the fish community when they adopted the Fish Community Objectives/or Lake Superior (Busiahn 1990), as directed in the Strategic Plan for Management of Great Lakes Fisheries . Signed by all agencies with management responsibilities for Great Lakes fisheries, the plan commits signatory agencies to plan for restoration and maintenance of desirable fish communities using a strategy of consensus . Fish Community Objectives for Lake Superior is a product of the consensus process. The fish community objectives serve as a template for State of the Lake reports for Lake Superior . It is expected that the fish community objectives will be revised, strengthened, and made more specific during the period between State of the Lake reports . Two State of Lake Superior reports have been produced by the Lake Superior Technical Committee (Hansen 1990, 1994) . The latter report includes recommendations for revision of the fish community objectives based on changing conditions and new knowledge.

s

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Lake Superior

By systematically setting objectives and reporting on progress for the whole-lake fish community, the Lake Superior Committee focuses attention on critical fisheries issues, and enhances communication and understanding on those issues among agency personnel, habitat protection agencies, political bodies, and the general public. Fish Community Objectives for Lake Superior presented eight statements summarizing actions needed to attain the desired fish community: Rehabilitate stocks of lake herring to historical levels of abundance for the purposes of lake trout rehabilitation, production of other predators, and fishery harvest . (Reference period: 1929-1943). Achieve a sustained annual yield of 4 million pounds of lake trout from naturally reproducing stocks (Note : historic yield probably included siscowets), and an unspecified yield of other salmonid predators, while maintaining a predator/prey balance which allow normal growth of lake trout. Manage exploitation of non-depleted stocks of other species to maintain stable self-sustaining status, for example lake whitefish, chubs (deepwater coregonids), suckers and walleye. Re-establish depleted stocks of other indigenous species, for example lake sturgeon, brook trout and walleye. Achieve a 50 percent reduction in parasitic-phase sea lamprey abundance by 2000 and a 90 percent reduction by 2010. (Reference point: 1986) Achieve no net loss of the productive capacity of habitats supporting Lake Superior fisheries . (No reference point identified; no habitat inventory currently available). Restore the productive capacity of habitats that have suffered damage. Reduce contaminants in all fish species to levels below consumption advisory levels. In addition to the objectives, the Lake Superior Committee identified issues that must be addressed in future joint planning for the fish community: Habitat quality and quantity are the ultimate constraints on future benefits ... from the fish community. ... Existing habitat [should be inventoried] for the purpose of measuring change, and ... fish habitat needs [should be placed] high on the agenda of environmental decision-makers. The management status of rainbow smelt must be agreed upon to guide coordinated fishery harvest and predator stocking strategies. The Lake Superior Committee must move toward a system of allocating forage stocks toward production of predators and fishery harvest.. . to guide stocking and harvest decisions. Lake Superior predator stocks can likely be totally supported by natural reproduction, though stocking may be necessary to provide harvest opportunities in some geographic areas. During later discussions, Lake Superior Committee agencies agreed that rainbow smelt are an undesirable species that should not be protected from harvest .

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Lake Superior;

To coordinate management of non-depleted stocks and restoration of depleted stocks, the Lake Superior Committee has established subcommittees dealing with walleye, Iake sturgeon, brook trout, and steelhead (anadromous rainbow trout), with the following charges : 1) exchange management information among Lake Superior agencies ; 2) develop a lakewide status report ; 3) develop lakewide objectives for inclusion in the Fish Community Objectives ; 4) develop a lakewide restoration plan to achieve the objectives ; and 5) report on progress through the State of the Lake reports. In 1986 the Lake Superior Committee approved the first Lake Trout Rehabilitation Plan for Lake Superior, including requirements for stocking of hatchery fish and for controlling fishing and sea lamprey-induced mortality . The goal of the plan, to achieve a 1 .8 million kilogram (4 million pound) yield of lake trout from self-sustaining stocks, was incorporated into the fish community objectives . One of the primary measures of progress toward the goal was a total annual mortality rate not exceeding 50 percent, as measured using standard gillnet assessment techniques in spring. (This figure is recognized as an index to mortality, because the standard technique over-estimates actual mortality.) Later the Lake Superior Committee revised the maximum allowable mortality rate downward to 45 percent, based on advice from the Lake Superior Technical Committee. At this writing, a revised Lake Trout Restoration Plan for Lake Superior has been drafted by the Lake Superior Technical Committee and is in the final stages of approval by the Lake Superior Committee . Quantitative goals for management of lake trout and associated species include: Restore self sustaining stocks of lake trout (including siscowets) that can yield an average of 1 .8 million kilograms (4 million pounds), the average annual yield in 1929-43, Restore lake herring abundance to historic levels that can sustain an annual yield of 4 .9 million kilograms (10.9 million pounds). Achieve recruitment of at least 3.6 million 1 .5-year-old lake trout lakewide, with adequate recruitment in each management area. Though Lake Superior fishery agencies have recognized the need to allocate forage stocks for production of predators and fishery harvest (Busiahn 1990), the scientific basis for allocation of forage is poorly developed . In Minnesota waters, Negus (1992) used a bioenergetics model to relate predation to available prey, and found large unexplained discrepancies . Estimates of available rainbow smelt and coregonines (lake herring and chubs) were far lower than estimates of consumed and harvested rainbow smelt and coregonines . Negus identified and prioritized information needed for effective bioenergetics modeling, the most critical being improved estimates of forage fish biomass at all depths and positions in the water column. Even with improved information, however, managers have few ways to allocate forage stocks . The sport and commercial harvest of predators and prey can be controlled to some degree . Lake Superior fishery managers have recommended that lake herring be protected through appropriate commercial fishing regulations so that stocks can recover, while supporting increased predation by lake trout (Hansen 1994) . However, lake herring harvest is not regulated in some jurisdictions ; in those cases, low market prices have provided the only real protection from the commercial fishery . Fishery management agencies have also agreed that rainbow smelt are an undesirable species that should not be protected from harvest . Strict regulations on lake trout harvest are in place throughout Lake Superior . Generally, State and Native American Tribal governments and their constituents have made great strides in controlling lake trout harvest. Stocking of predators also provides some control over the allocation of forage . The Lake Superior fishery management agencies have recognized that predator stocks can likely be totally supported by natural reproduction, though stocking may be necessary to provide harvest opportunities in some geographic areas (Busiahn 1990) . More recently,

138

Lake Superior

fishery managers jointly recommended that stocking programs and fisheries should not compromise any naturally reproducing salmonine population, including lake trout (Hansen 1994) . Lake trout stocking criteria have been proposed in the revised restoration plan . Stocking of other salmonids continues in most jurisdictions, but managers and many of the general public increasingly realize the limitations of stocking. Implementation of fishery habitat objectives "no net loss of productive capacity and restoration of damaged habitats" is hampered by inadequate habitat inventories (Hansen 1994) . General inventories of important spawning grounds have been completed, partly based on anecdotal information (Coberly and Horrall 1980 ; Goodyear et al. 1982). However, few inventories exist for fish habitat in tributaries and wetlands . Changes in fish habitats need to be monitored and incorporated into fishery management programs to prevent net loss . Mitigation should be incorporated into any projects involving habitat alteration . However, physical alteration of fish habitat in Lake Superior should be Iimited to cases of restoration of degraded habitat (Busiahn 1990). Restoration of degraded habitat is being pursued through designation of Areas of Concern to be the subject of Remedial Action Plans. Stage I of the Remedial Action Plan process describes the intensity and scope of environmental problems and the causes for the impairment . Stage II identifies remedial measures required to restore beneficial uses. Four Areas of Concern have been designated in Ontario : Peninsula Harbor, Jackfish Bay, Nipigon Bay, and Thunder Bay. The Remedial Action Plan process in each of these areas has completed Stage I and has proceeded to Stage II . In Michigan, the Areas of Concern are Torch Lake and Deer Lake-Carp Creek/River . The Remedial Action Plans for these areas have been submitted to the International Joint Commission for review and have progressed toward finalization. The St . Louis River system is an Area of Concern shared by the States of Minnesota and Wisconsin . This Remedial Action Plan has completed Stage I and proceeded to Stage II (International Joint Commission 1991). Fishery agencies have also addressed habitat concerns through active involvement in hydropower relicensing processes. Numerous fisheries studies have been done to address the impact of dams (Hansen 1994) . Fishery agencies have advocated for licenses contingent on a change in operation to run-of-the-river flows that should benefit migratory species. Ecosystem objectives for Lake Superior were also established by the U .S. and Canada in the Great Lakes Water Quality Agreement of 1978, as amended (International Joint Commission 1989) . The nations agreed that: Lake Superior should be maintained as a balanced and stable oligotrophic ecosystem with lake trout as the top aquatic predator of a cold-water community and the Diporeia hoyi as a key organism in the food chain ... The Agreement further specified that lake trout and Diporeia would be used as indicators of ecosystem health . Lake trout should have productivity greater than 0 .38 kilograms/hectare (0 .34 pounds/acre) from stable, self-sustaining stocks, and be "free from contaminants at concentrations that adversely affect the trout themselves or the quality of the harvested products ." Pontoporeia hoyi should be maintained throughout the entire lake at densities of 220-320 per square meter (262-381 per square yard) in depths less than 100 meters (328 feet), and 30-160 per square meter (36-190 per square yard) at depths greater than 100 meters (328 feet) .

139 k Basin-wide .Research

Basin-wide Research on Fish Population Dynamics: A Critical Evaluation of Historical Data

The Great Lakes Science Center (Center) of the National Biological Service has long played a key role in conducting research on fish communities of the Great Lakes . The Center, in cooperation with its Great Lakes partners, initiated three research projects in 1992: the restoration ecology of lake trout, • the dynamics of Great Lakes forage-fish communities, and the community dynamics of commercially-harvested species in the Great Lakes. -

The primary goals of these studies are to provide insight on factors associated with changes in fish population abundance, and to aid in the identification of impediments to restoration of native Great Lakes species, such as lake trout. The following sections describe basin-wide research efforts under the Act . These projects address the second objective of The Study by critically evaluating the sufficiency of historical databases in addressing questions on population dynamics of Great Lakes fishes . Research activities continue on all three projects and therefore final results can not be described here.

Restoration Ecology of Lake Trout In the Great Lakes, efforts to restore lake trout stocks have focused on supplemental stocking of hatchery fish in areas that sustain remnant populations of naturally reproduced fish (Lake Superior), and in areas that were traditionally used by native lake trout (Lake Michigan ; see, e .g., Lake Michigan Lake Trout Technical Committee 1985, or Eck and Brown 1985) . One approach useful in ecological studies is to compare and contrast populations from two or more environments (e.g ., two or more lakes), thereby delineating commonalities and contributing to an understanding of fundamental processes that govern populations (such as intrinsic birth rates and death rates) . Comparative approaches are important in determining which part of the life cycle is critical to the persistence of the species and therefore, determining which restoration efforts will most likely succeed . Studies on the restoration ecology of native species focus on understanding the factors crucial to the recovery of these species and their habitats . An evaluation and comparison of the survival of hatchery and native lake trout will contribute to the understanding of the population biology of this species . The reestablishment and perpetuation of lake trout stocks in the Great Lakes may be jeopardized if researchers and managers continue to approach the challenge single-handedly . Eventually, populations may be restored, but the time required to achieve the goal and the lessons learned may be lost along the way. Alternatively, through cooperative efforts with our partners, the information necessary to identify the factors important to lake trout restoration can be gathered and analyzed. Two study areas have been identified in the Great Lakes region : one has sustained a small, but growing population of native lake trout (Gull Island Shoal, Lake Superior), and the other is composed entirely of hatchery fish (Clay Banks, Lake Michigan) . Prior to 1976, lake trout populations in the Gull Island Shoal area of Lake Superior had been subjected to natural and fishing mortality . In 1976, a refuge was established in the area (Swanson and Swedberg 1980) to restrict fishing; lake trout in the refuge area were subjected only to natural and sea lamprey induced mortality . Efforts to supplement and enhance population abundance at Gull Island Shoal have focused on the release of hatchery fish and the maintenance of the refuge . A study of the survival rates of this population before and after establishment of

140

Basin-wide Research,

the refuge (in conjunction with estimates of population abundance) would reveal the effect of removing most of the component of mortality due to fishing . Knowledge of the survival rate in the absence of fishing mortality would be beneficial to those wishing to know the time required for the population to reach a particular abundance, size, or age structure. The Clay Banks area of Lake Michigan once supported a viable native lake trout population . Now, all lake trout in this lake are hatchery fish . The harvest of lake trout in Lake Michigan, which is restricted to sport fisheries and commercial fisheries operated by Native Americans, is controlled by a quota system (Lake Michigan Lake Trout Technical Committee 1985) . Thus, this population experiences both natural, sea lamprey induced, and fishing mortality. Survival rates of Clay Banks fish will be compared to those for Lake Superior hatchery fish . When considered together with stocking rates, survival rate estimates can be used directly by resource managers to evaluate the likelihood of attaining the long-term goal of a self-sustaining lake trout population, and to establish harvest quotas for this species (Lake Michigan Lake Trout Technical Committee 1985). Lake trout populations in Lakes Superior and Michigan have been monitored annually by resource management agencies in the region . Typically, assessment surveys are conducted annually or semi-annually and catch rates are used as indices of abundance . In addition, mark-recapture studies have been conducted to obtain information on survival rates . Mark-recapture studies have been conducted annually in Lake Superior in the Gull Island Shoal area since 1969, and in Lake Michigan in the Clay Banks area since 1983. The purpose of the research study is to estimate survival rates of adult lake trout in Lake Superior and Lake Michigan and to evaluate the effect of the Gull Island Shoal refuge on survival rates . Secondarily, the study will serve to compare survival rates of hatchery and native fish where they co-occur (Gull Island Shoal), and to compare survival rates of hatchery fish from two lakes . These results will permit resource agencies to evaluate the efficacy of lake trout stocking programs and the role of refuges in management of lake trout. In 1992, as a result of collaborative efforts with the Bayfield and Sturgeon Bay offices of the Wisconsin Department of Natural Resources, researchers at the Center began work on two long-term data sets describing an intensive tagrecapture program. Initially, research activities focused on designing the study, and acquiring and reformatting information for subsequent analysis . The task was not trivial and is likely to be a reason contributing to the few (and unsuccessful) previous attempts at long-term, basin-wide studies of lake trout survival. Until 1992, data existed in various stages of readiness for computer analysis . Some of the data (1969-1975) for Lake Superior existed only on field sheets maintained at the Bayfield office ; these were coded and entered into computer files . Another portion of the data existed in modified ASCII format on Apple diskettes ; data on these disks were transferred from Apple-compatible media to IBM-compatible media . The remainder of the data from Lake Superior existed in Lotus spreadsheets ; these data required translation to a dBaselV spreadsheet . The three databases were translated into a file structure and format compatible with the software selected for analysis (the SAS system for OS/ 2) . Data checking, verification, modification, management, and preliminary analyses were performed with the SAS system. Quality assurance tests were performed with the data, including verification of codes (initial tag numbers, tag numbers on recaptured fish, length, sex, maturity stage, and date), and elimination of records of fish tagged by other agencies or in other areas . Additionally, fish that were part of several double-tagging experiments were identified and data on these fish were reformatted to permit accurate tracking of tag shedding information . A large number of modifications of the primary database was made after verification with field sheets by Wisconsin Department of Natural Resources personnel . All modifications and deletions were recorded .



141

Basin wide?Research`

The data collected from the Clay Banks population were received as dBase files ; these were read directly into a SAS data set. Data checking included verification of coded information (species, tag numbers, tag type, whether the fish was a first capture or recapture, location, length, and date) . All modifications to the data set were performed after verification by personnel who collected the data, and records were maintained of such changes. Survival models, which will be fit to the lake trout data, require input on the number of tagged fish that are subsequently recaptured . This information will be used to construct capture histories which are the primary data used in tag-recapture models to estimate survival rate (Burnham et al. 1987; Nichols 1992). Prior to estimating survival rates, it is critical to test the assumption that tags are not shed ; e.g., once inserted into a fish, a tag is not damaged or shed. If fish lose a tag, then the number of recaptured fish bearing a tag will be less that the actual number of fish that were originally tagged and subsequently recaptured . Thus, tag shedding rates are necessary for adjustment of survival rate estimates ; otherwise, survival rates are underestimated . Because the structure of the Lake Superior database did not permit extraction of information concerning fish tagged with more than one tag, the SAS data set was transformed into a relational database (Fabrizio and Nelson 1994) . Using Structured Query Language in SAS for OS/2, information on double-tagged fish was compiled . These data were used to estimate tag shedding rates . In Lake Superior, three types of tags were used, so three shedding rates were estimated . A twoparameter nonlinear model was developed to describe long-term tag shedding rates for lake trout . In general, about 35 percent of the tags attached to lake trout appear to be permanently affixed ; the remaining 65 percent are shed at annual rates varying between 25 .9 percent and 48 .1 percent, depending on the type of tag (Figure 77) . Tag shedding rates will be used to adjust estimates of survival rates of lake trout. FD-67

---• FD-67C

•""'• FD-6BBC

0)

0 .70 a) 0) tU

0

..

0 .60-

-~'

0 .500 .40• 0 .30.

rf

~r

'

i

0 .20- - rr . =r 0 .100

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0 .00 0

2

4

6

8

10

12

14

16

18

Time (years) Figure 77 . Probability of tag shedding for three types of anchor tags used to tag individual lake trout from Gull Island Shoal, Lake Superior.

Dynamics of Great Lakes Forage fish Communities Great Lakes fish communities are part of a complex ecosystem that has been subjected to dramatic changes since the early to mid-19th century . Fish communities today are composed of a mixture of exotic and native species, reflecting the outcome of purposeful introductions and undesirable invasions . State and federal hatcheries have been releasing

142

Basin wide Research

large numbers of young non-native salmonids (e .g ., coho salmon, chinook salmon, rainbow trout or steelhead, and brown trout) into the Great Lakes for about 25 years (Wells and McLain 1972) . As hatchery techniques and production capabilities improved, more and more fish were stocked . For many years, it was assumed that the forage fish base in the Great Lakes was sufficient to sustain growth of these salmonids and indeed, a put-grow-and-take fishery was successfully established . Now, however, agency personnel are beginning to question the adequacy of the forage base in terms of the quantity (biomass) of forage fish available and the species composition of the forage fish community. In response, the Great Lakes Fishery Commission recently supported a modeling exercise to explore the effect of stocking Pacific salmonids on forage fish populations of Lake Michigan . The study, referred to as the SIMPLE [Sustainability of Intensely Managed Populations in Lake Ecosystems] modeling exercise, provided predictions of population size for the major fish species in the Great Lakes under various stocking scenarios . Results of the execution of the SIMPLE model have been used to guide managers in decisions regarding continued stocking of non-native salmonids . The key role of forage fish species (alewife, bloater, rainbow smelt, and deepwater sculpin) in supplying energy to predators was continually highlighted by these exercises, and the negative feedback between stocking predatory fish and sustainability of prey populations was readily apparent. Models of fish community dynamics, such as the SIMPLE model, rely heavily on fisheries data. The Center, along with other agencies, has been assembling and collecting such data . As information becomes more precise and our understanding of the factors that control community interactions improves, the utility of models improve . At this stage, most models (including SIMPLE) do not take into account possible interactions among forage fish species. Researchers at the Center, working cooperatively with partners at Michigan State University, can provide a better understanding of fish community dynamics by identifying the factors and interactions that are critical to controlling the abundance of forage fish species . Modelers can then "re-tune" models so as to reflect current scientific understanding of the population dynamics of forage species, thereby providing a more accurate tool for making fishery management decisions and for evaluating fish community objectives for the Great Lakes. The purpose of this study is to identify and describe those factors contributing to changes in population abundance of the major forage species in Lake Michigan . Important biotic factors that may affect fish abundance include growth, fecundity, mortality, predation, competition, and food availability (Hewett and Stewart 1989 ; Jude et al. 1987; Miller et al. 1990) . Abiotic phenomena such as temperature, duration of ice cover, and winter severity could affect fish abundance as well (Garling and Masterson 1985 ; Henderson and Brown 1985 ; Scavia et al. 1986; Taylor et al. 1987). Recruitment of alewife was higher after warm growing seasons and mild winters, but cold winters tended to suppress alewife recruitment (Eck and Brown 1985) . Both biotic and abiotic effects may work in concert . For example, the abundance of rainbow smelt in Green Bay, Lake Michigan, was related to spawner abundance, mean solar intensity in April and May of the previous year, and mean air temperature in April of the previous year (Sluka 1991). Sainsbury's (1988) observation that a single approach to understanding fish community dynamics is not "universally accepted" provides the motivation to examine fish communities in an empirical, exploratory manner . As a complement to the bioenergetics approach currently pursued by several Great Lakes researchers (e .g., Jones et al 1993), this study will focus on empirical models based on stock assessment data for Great Lakes fishes . The approach is a time series analysis, a statistical technique first developed and described for forecasting economic indicators. A time series of fish population abundances will be evaluated for indications of possible abiotic and biotic influences. Abundance indices for key species -- alewife, bloater, and rainbow smelt - will be examined from Lake Michigan. This lake was selected first because of the importance of sport fisheries for non-native salmonids and the need to provide additional information to the SIMPLE model. The approach is to identify common cycles in the relative abundance of forage fish species, to determine community-wide patterns in abundance, and to relate these patterns to abiotic factors . Skud (1982) demonstrated the importance of considering multispecies assemblages when examining the role of abiotic factors : he found that climatic factors can affect species abundance but that a species' response to

143

Bas n wide Research

abiotic change was dependent on its position in the dominance hierarchy . Thus, multispecies models similar to those described in Stone and Cohen (1990) will be developed and the resultant models will permit testing and formulation of hypotheses concerning perturbations of aquatic ecosystems. The nature of this study is retrospective because it relies on analysis of data that are already collected . Several sources of data were identified and will be used in this investigation: the Center has information on the relative abundance of forage fish species for Lake Michigan based on bottom trawl surveys conducted annually in the fall; various agencies and private vendors have collected information on climatic factors ; and State and international agencies have compiled data on stocking rates for salmonid predators in the Great Lakes. Annual fish abundance data from standardized assessment surveys include information on total numbers, weight, and effort expended for each species at each sampling site. Sampling sites and methods of collection were selected so as to remain constant throughout the period of study - 1977 to 1991 . Fish abundance data from assessment surveys are maintained at the Center on a Data General minicomputer . Information on species, port, date, depth of station, numbers, weight, length frequencies, life stage, and bottom temperature was downloaded onto ASCII files and sent to cooperators at the Department of Fisheries and Wildlife, Michigan State University, for statistical analysis. Abundance indices as indicated by catch rates for Lake Michigan alewife, bloater, and rainbow smelt were examined for sources of variation . Large variations in catch rates could result from an inadequate survey design, measurement error, or noise . The survey design was identified and changes in design were noted for their effect on variation in catch rates . Trawl surveys were consistent between 1977 and 1991 at eight stations (Frankfort, Ludington, Saugatuck, Benton Harbor, Waukegan, Port Washington, Sturgeon Bay, and Manistique), and between 9-110 meters (30-361 feet). The effect of using three vessels to perform bottom trawling was tested and found to be insignificant . Catch data from the three vessels can therefore be used to monitor abundance of prey fishes in Lake Michigan. Data representing biotic factors were identified and include creel survey estimates of salmonid abundance (Wisconsin Department of Natural Resources and Michigan Department of Natural Resources), and annual stocking rates for salmonids (Great Lakes Fishery Commission) . Four States surrounding Lake Michigan have contributed to stocking of Pacific salmonids (Michigan, Wisconsin, Indiana and Illinois), and appropriate agency personnel were contacted for permission to access the databases. Annual statistical summaries of weather conditions (e .g ., air temperature, cooling degree days, heating degree days) were obtained for six weather stations along Lake Michigan (Benton Harbor, Ludington, Waukegan, Port Washington, Sturgeon Bay, and Manistique) . Although surface water temperatures are more likely to accurately portray temperature cycles in the lakes, data from the National Data Buoy Center are available only for the 10-year period, 1979-1989 (Lesht and Brandner 1992) . Therefore, air temperatures will be used as surrogates for surface water temperatures . (Additionally, weather buoys provide daily surface water temperatures and this temporal scale may be too fine to be readily used in this study .) Because of the high variability in temperature data, a robust model (Cleveland 1979) was used to identify trends and cycles in weather data . A temperature gradient exists over the lake such that the most southern stations are the warmest (Figure 78) . The overall trend in air temperature can be seen from analysis of the Sturgeon Bay data set, which covers a period of about 90 years : there has been a pronounced warming trend in this region, with a maximum rise between 1940 and 1960 followed by a short cooling period in the 1970s . This cooling period was a feature of all six time series examined (Figure 78) . The weather over Lake Michigan is regulated by the position of the polar jet front (Eichenlaub 1979), such that mean air temperatures may be depressed or increased with changes in jet stream position .



144

Basin-wide Research"

10 -

1 2 3 4 5 6

8

Benton Harbor Waukegan Ludington Port Washington Sturgeon Bay Manistique

6-

4-

1920

1940

1960

1980

Figure 78 . Time series of annual mean air temperature for six stations around Lake Michigan. The smoothed lines are LOWESS lines . LOWESS is an abbreviation for robust locally weighted regression ; it is used to graphically display a pattern in noisy data.

Preliminary exploratory analysis of forage fish abundance has focused on identification of the depth, geographical, and temporal distribution of forage fish biomass in Lake Michigan . Catch rates of the three major species are similar among ports sampled in Lake Michigan and no striking patterns exist . However, catch rates vary by depth for each species . Alewife abundance is fairly consistent with depth except that numbers are more variable in shallower waters from 5-30 meters (16-98 feet) . Rainbow smelt abundance is higher at intermediate depths from 18-55 meters (59-180 feet) and begins to decrease at 46 meters (151 feet) ; few rainbow smelt are taken in deep waters. The distribution of bloater biomass is similar to that of rainbow smelt . Temporal changes in abundance of these three species indicated a general increase in bloater abundance in the early- to mid-1980s, coupled with a decrease in alewife abundance beginning in the mid- 1980s (Figures 79 and 80) . Rainbow smelt abundance remained fairly constant, but low.

1 2 3 4

0 0 N

g

5 6 7 8

Benton Harbor Ludington Manistique Saugatuck Waukegan Port Washington Sturgeon Bay Frankfort

Smoothed adult bloaters relative abundance

a

1970

1975

1980

1985

1990

Figure 79 . Relative abundance of bloater as indicated by bottom trawl surveys at eight ports. The lines were smoothed using LOWESS . LOWESS is an abbreviation for robust locally weighted regression ; it is used to graphically display a pattern in noisy data.



145

Basin-wide Research '

u]t alewives undance

0 0 Lb

2 3

Benton Harbor Ludington Manistique

4 5 6 7 8

Saugatuck Waukegan Port Washington Sturgeon Bay Frankfort

0

o1970

1975

1980

1985

1990

Figure 80 . Relative abundance of alewife as indicated by bottom trawl surveys at eight ports. The lines were smoothed using LOWESS . LOWESS is an abbreviation for robust locally weighted regression ; it is used to graphically display a pattern in noisy data.

Changes in length-frequencies of the three key species have been examined ; most notable, the average size of bloater decreased from 1973 to the mid-1980s ; rainbow smelt and alewife show no changes in average size through time. Formal time series analysis will be used to decompose temporal fluctuations in fish abundance into a trend plus irregular fluctuations about the trend . Likewise, a time series analysis of air temperature will yield information on a trend, a seasonal cycle, and irregular fluctuations . Once a trend or cycle is identified, the pattern of residuals must be investigated: these residuals often reveal additional cyclic changes, such as oscillations of longer periods . A technique known as spectral analysis can then be used to determine the presence of dominant (significant) cycles . Dominant cycles in fish abundance will be cross-correlated with cycles or trends determined from time series analysis of biotic and abiotic factors . Additionally, lagged cross-correlations of fish abundances with weather data (air temperature) may provide insight on the time frame during which fish are most sensitive to changes in weather conditions . Simple and lagged cross-correlations of forage fish abundance and stocking indices will be computed to examine interactions between prey fish and their stocked predators.

Community Dynamics of Commercially-harvested Fishes The goal of this study is similar to that described in the previous section on Dynamics of Great Lakes Forage-Fish Communities, except that it is not restricted to Lake Michigan . This is because commercial fishery records for all five Great Lakes will be used to investigate biotic interactions among fish populations in each lake . As in the previously described study, a time series analysis will be performed (assuming the data are sufficient) . Commercial fishery records have been published for key species in the Great Lakes by the Department of Commerce and the Department of the Interior, however, there are three major difficulties with these records: • the type of information published changes through time (depending on which agency handled the data), • the time series of data is incomplete (some years, particularly the years during World War II, are missing entirely), and • the accuracy of these data is unknown .

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Basin-wide Research

To use commercial fishery data for analysis of population dynamics, the data must include information on species, total weight landed, and effort expended by gear type for each lake . Furthermore, these data must be available on at least an annual basis and in a continuous series for any given species . The availability of a complete series of commercial catch and effort data from all five lakes was assessed, and data for several species were selected on the basis of total Table 12 . Commercially-important species in the Great Lakes . An "X" indicates inclusion in the data set describing the fish community for a particular lake. Species

Lake Superior

Alewife

Michigan

Huron

Brie

Blue pike

x

Carp

x

x

Chubs

x

x

x

Lake herring

x

x

x

Lake trout

x

x

x

Lake whitefish

x

x

x

Rainbow smelt

x

x

x x

x

x

Walleye Yellow perch

Ontario

x

x x

x

x x

x

x

x

catch and species dominance in the overall harvest for each lake (Table 12) . Commercial catch data for Great Lakes fisheries were first published for 1917 . These annual reports include total annual catch and beginning in 1927, effort by gear for each State and lake . Extensive searches uncovered several limitations of the commercial fishery data for the Great Lakes. Incomplete catch data were published in 1923-1925, 1933, and 1935 : total catch by species was not reported by gear in these summary reports, which were published by the U .S . Department of Commerce, Bureau of Fisheries. Effort data were not reported prior to 1927 or in 1941-1949, and 1952-1953 . In addition, catch was not documented by gear prior to 1930. The U.S . Fish and Wildlife Service, Bureau of Commercial Fisheries, published consistent and complete records from 1954 to 1967 . From 1968 to 1970, the National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service, published similar records. Since 1971, the Center has compiled and entered annual summaries of commercial catch and effort data into computer data files (ASCII and SAS files) ; the files are delivered to NOAA for subsequent publication . In general, the information available in computer files is more detailed than that published in annual summaries. This turnover of reporting responsibility spawned several non-trivial changes in the manner in which records were maintained and in the amount of information reported . Considering these observations as a whole, it is clear that complete data compilation and reporting by species for a specific gear type began, in effect, in 1954 . Hile (1962) provides a description of methods used to report commercial fishing statistics for the early years (e .g ., estimation of

147

Basde Research;

effective fishing effort, delineation of statistical districts and exceptions to standard procedures). Although other summaries of annual commercial fisheries statistics exist (e .g., Comptroller General 1977 and Baldwin et al. 1979), these typically do not include effort data and are generally restricted to a few species per lake . In addition to annual sources of data, the Center has a microfiche library of monthly catch and effort forms completed by licensed commercial fishers . None of this information has been computerized in a monthly form ; it has been estimated that 2 person-years for each year of data are required to complete coding and entry of these records (A . Frank and E. Moore, personal communication) . The availability of such records is noted here for possible future research needs. All annual catch and effort data (by gear) for the years 1954 to 1970 were entered manually from published records (e.g., Anderson and Power 1956) into EXCEL spreadsheet files . These records are complete for all species identified in Table 12 and for all five lakes . Commercial fishery data from 1971 to 1992 were keypunched into ASCII files by Center personnel using monthly reports from commercial fishers . The 1971-1992 data were available as summarized SAS files which had been stored in a compressed format. Attempts were made to use the summarized SAS file information on catch and effort, but it was determined that total effort estimates by gear type were incalculable, and mesh size for important gear types was unavailable, although all this information existed in the original ASCII files . Therefore, catch and effort data were extracted from the original ASCII files for 1971-1992 . (Comparisons of total effort estimates from corresponding SAS and ASCII files indicated inaccurate estimates of total effort from the SAS summaries -- some estimates were biased by an order of magnitude.) The database management system on the Data General minicomputer at the Center was used to prepare ASCII files for transfer to a personal computer . On the personal computer, the files were reformatted into a relational database using Structured Query Language in SAS . The resulting database consisted of four tables : Catch (containing landings by species and gear), Effort (containing effort by gear), Identify (containing operation codes and date) and Price (containing monetary value of landings) . Other data were included in these tables and all data could be accessed using a unique identification variable assigned to each net operation . Some of the Wisconsin commercial fishery data from recent years (1989 to 1992) required additional re-formatting prior to table construction because the information recorded in those years was different from previous years. Preliminary quality control checks revealed possible inconsistencies in measurement units used to report catch: landings for some species were reported as round weight, some as dressed weight, and others as filleted weights. Commercial fishery biologists from all States using the various reporting units were contacted to verify use and determine appropriate conversion factors so that all weights could be converted to round weights. Additional quality control checks are required prior to using the tables to extract catch per unit of effort information from the commercial fisheries . Because the database is so large and requires intensive computing resources, these checks have not yet been possible . Plans to implement a local-area network and purchase a more powerful PC for the Center should improve accessibility . Once the `hardware' problems are solved, the 1971-1992 data will be summarized and merged with the pre-1970 database . Time series analyses will be attempted with the complete database of commercial catch and effort (1954-1992) . It should be noted that catch and effort estimates from 1971-1992 will be more detailed than those available from 1954 to 1970 . Also, total effort for 1954-1970 was reported across species, whereas in 1971-1992, it was reported for each of the key species identified in Table VII-1 . Some of these inconsistencies must be addressed in future research .

148

Evaluation of Plans

Basin-wide Evaluation of Existing Management Plans Interagency Fishery Management Plans The following material is excerpted from Dochoda and Koonce (1994) . In all cases "Strategic Plan" has been replaced with "Strategic Plan for the Management of Great Lakes Fisheries" and "Commission" has been replaced with Great Lakes Fishery Commission" to be consistent with the rest of this report. The Strategic Plan for the Management of Great Lakes Fisheries can be used by Great Lakes fishery managers to anticipate issues and opportunities, to react collectively to crises and opportunities, and to be more efficient zn management and assessment . The Strategic Plan for the Management of Great Lakes Fisheries can be used as a coordination vehicle among fishery managers from various jurisdictions and as a communication tool for informing other users or managers of the Great Lakes about the impacts of their activities or about fisheries' needs . In the Strategic Plan for the Management of Great Lakes Fisheries' fourteen year history, fish managers have accomplished all of the above, unevenly but consistently enough to demonstrate the promise of the Strategic Plan for the Management of Great Lakes Fisheries approach. Great Lakes managers have three primary avenues for effecting change in fish populations : (1) balancing predators and prey (e .g., catch regulation, stocking, and sea lamprey control) ; (2) preventing unplanned or ill-considered introductions ; and (3) optimizing habitat . This section will review examples of managers' successes in accomplishing the above in fish management planning, in fish management coordination, and in fisheries and environmental management coordination, all tasks set for them by the Strategic Plan for the Management of Great Lakes Fisheries . Contributions and shortcomings of the Strategic Plan for the Management of Great Lakes Fisheries and its three principal actors (agencies, Lake Committees, and the Great Lakes Fishery Commission) are discussed primarily from a Great Lakes Fishery Commission staff perspective. Fish management planning To anticipate issues and opportunities to balance predator and prey, to prevent unplanned or ill-considered introductions, and to optimize habitat, fish managers and users must first have agreed on fish community objectives for a particular lake . Second, information must have been gathered and analyzed in such a mariner that issues and opportunities for management action have been recognized . Thirteen years after the Strategic Plan for the Management of Great Lakes Fisheries was signed, all but two Lake Committees have common objectives for their fish communities. Environmental objectives are the next significant task under the Strategic Plan for the Management of Great Lakes Fisheries. The development of fish community objectives has been very slow . Agencies might have developed fish community objectives more quickly had they established this task as a priority with agency representatives on Lake Committees, perhaps by explicitly listing the production of objectives in Lake Committee representatives' work plans in their home agencies and by providing planners to assist Lake Committees . Lake Committees did not at first recognize that approved fish community objectives would not only ease their own individual management efforts, but would influence allied disciplines such as environmental management, as well . For example, Lake Huron's lake trout rehabilitation objective and related plan became the basis for a 1985 consent decree establishing the management framework for all the fisheries in the treaty area, thereby strengthening efforts toward a common objective for the resource and easing a potentially volatile situation. A state of the lake report is required of each Lake Committee by the Committee of the Whole every three years beginning in 1990 . Seen as a measure of accountability to agency directors, this reporting requirement may well be the most effective mechanism to ensure that fish community objectives reflect managers' current beliefs, that fishery programs remain true to their objectives, and that policy makers, both fishery and environmental managers, as well as the general public can be well briefed on the fisheries, the status of stocks, and their needs . In 1990, Lakes Superior and Ontario produced state of the lake reports, although the Lake Ontario report could have been even more infor-

149

Evaluation of Plans

mative with finalized fish community objectives . Complete reporting did not occur in 1993, due to preoccupation with fish community and other management concerns, but the commitment is there, and full reporting by all Lake Committees is expected by 1996. Technical support by both the Great Lakes Fishery Commission and the technical subcommittees of the Lake Committees has been crucial to the successful implementation of the Strategic Plan for the Management of Great Lakes Fisheries . As described earlier, technical subcommittees have been instrumental in gathering and analyzing information in such a manner that issues and opportunities for management are recognized and can be addressed . Technical subcommittees have made substantial contributions to Lake Committee products, such as fish community objectives on Lake Superior, lake trout rehabilitation plans on the four oligotrophic lakes, and Total Allowable Catch resolutions for Lake Erie . The Great Lakes Fishery Commission has played . an active support role to Lake Committees and technical subcommittees in development of fish community models, in support of agency development of common databases, in technical transfer of new science, in analysis of issues such as introduction of exotic organisms, and in the role of purchasing agent for standard gear. Lakes Erie and Superior have been particularly successful under the Strategic Plan or the Management of Great Lakes Fisheries . Both lakes are blessed with (1) largely intact native fish communities (which could be irrevocably lost without collective stewardship) [eastern basin of Lake Erie native fish community is an exception], (2) a binational character (that seems to engender a more formal consultative approach) and (3) a .critical mass of agencies (and thus . biologists to staff technical subcommittees) . Agency commitment to joint initiatives appears strongest on Lake Erie, where agencies expect both management and assessment to be integrated with activities of lake and technical subcommittees. Coordinated fisheries management Lake Committees have been effective in reacting to crises and opportunities such as : (1) responding to the depletion of bloaters and other deepwater ciscoes in Lake Michigan with a lakewide ban on chub fishin ; (2) responding to the closure of the Lake Erie walleye fishery because of mercury contamination by developing an jointly implementing a Total Allowable Catch that, upon reopening, allowed complete rehabilitation of an exhausted fishery ; (3) following up on lake trout rehabilitation plans by establishing and stocking refuges ; and (4) preventing the establishment in the Great Lakes of several non-endemic fish diseases. The Strategic Plan for the Management of Great Lakes Fisheries consensus strategy has been effectively applied to management of fish introductions and to disease control . Agencies, obliged under the Strategic Plan for the Management of Great Lakes Fisheries to achieve consensus when any management proposal may significantly influence the interests of another jurisdiction, consult with each other when planning an introduction . Planned introductions of striped bass, grass carp and arctic char have been reconsidered after concerns were expressed by other Great Lakes jurisdictions. However, more progress is needed to deal with introductions made for reasons unrelated to management of the Great Lakes fishery . Lake Committees have adopted inter-agency consultation procedures for all jurisdictions to use when contemplating a new introduction . Unfortunately, collective stewardship cannot be fully effective unless either it is captured in agencies ' internal procedures when contemplating irrevocable changes to the ecosystem or it is forcefully communicated to politicians and the public. Non-binding arbitration by the Great Lakes Fishery Commission is the fallback under the Strategic Plan for the Management of Great Lakes Fisheries for management agencies which cannot agree on management objectives or actions for a shared resource . The Strategic Plan for the Management of Great Lakes Fisheries states that if a consensus decision cannot be reached by a Lake Committee "the problem will be taken to the Great Lakes Fishery Commission for arbitration (non-binding) at the request of one or more of the parties in the dispute at the lake committees level ." In 1992, the Ohio Department of Natural Resources requested that the Great Lakes Fishery Commission arbitrate a dispute between Ohio and the Ontario Ministry of Natural Resources to decide whether the Lake Erie yellow perch harvest should be shared on a historical use or a geographical area basis . The Great Lakes Fishery Commission was unable to serve as arbitrator because of concerns raised by the Canadian Party to the Convention which created the Great Lakes Fishery Commission . This withholding of arbitration services is of significant concern to the Committee of the Whole .

150 `

'Evacuation of Plans

Ecosystem Partnership Coordination The Service, in partnership with the Great Lakes Fishery Commission and the U .S. Environmental Protection Agency, created a temporary position to explore the basis for developing stronger partnerships in setting and implementing common objectives for ecosystem management of the Great Lakes. As originally conceived, the position was to focus on the integration of Lakewide Management Plans and Fish Management Plans for Lake Michigan and Lake Ontario . Approaches to these two planning activities, however, proved to be too disparate and unconsolidated for integration . The Lake Michigan Lakewide Management Plans for Critical Pollutants had a narrow focus on pollution, and neither the U .S . EPA or Environment Canada had an active strategy to implement a systematic and comprehensive ecosystem approach to restoration of the chemical, physical, and biological integrity of the Great Lakes . Although committed to an ecosystem approach, the highest priority concern of water quality managers is to reduce pollution of the Great Lakes by critical pollutants . The most pressing environmental concerns of -fish managers, in contrast, are related to habitat and conventional pollutants . Nevertheless, fish managers had yet to develop integrated Fish Management Plans that linked Fish Community Objectives and the Environmental Objectives required to achieve the goals of fishery management . In view of these differences in approach, the primary function of the Ecosystem Partnership Coordination position, therefore, became analysis of the impediments to ecosystem management in the Great Lakes and preliminary work to assist the development of institutional coordination. Despite these differences, water quality and fish managers share a broad complementarity in approach to ecosystem management . Water quality managers focus primarily on external stresses that cause various impairments of beneficial uses of the Great Lakes, and fish managers are concerned primarily with restoration and maintenance of fish populations of the open waters of the Great Lakes . In attempting to identify the environmental objectives necessary to achieve their stated fish community objectives, fish managers are providing criteria for restoration of beneficial uses. Water quality managers need such criteria to bound levels of stress reduction (i .e. pollution loading restrictions and levels of required habitat remediation) in order to achieve operational guidelines for restoring the integrity of the ecosystems of the Great Lakes . This complementarity of approach provides an opportunity to explore more iterative or evolutionary approaches to establishing end points for the ecosystem objectives necessary to implement a more strategic plan for ecosystem management . To move toward a more strategic integration of ecosystem management, will require : 1) a broad commitment to joint management by water quality and fish managers, 2) an explicit attempt to derive an operational set of interim environmental objectives and 3) the design of joint management activities (Koonce 1994).

151

mpediments

Impediments to Restoring a Healthy Ecosystem Philosophical, Ethical and Decision-making Considerations Lack of historic knowledge and expertise Due to lack of time and a continuing need to address emergent challenges, natural resource managers do not, as a rule, have the resources to study the failures of their own decisions . Without applying institutional memory and learning there is a tendency to repeat the mistakes of the past . Natural resource management, as a discipline, needs better mechanisms to apply historic knowledge. Managers often believe that recommendations and decisions based on sound scientific study are most justified, but realize that human needs expressed through political systems can impact actions . Natural resource managers are, by their training, predisposed to readily implement actions only when scientific evidence is complete and unequivocal. However, because large natural systems are unique and inherently complex, they are not amenable to science-based experimental design. When management decisions are made and techniques that affect the system applied, there is absolutely no potential for replication and control ; cause and effect relationships are obscured and subject to misinterpretation . Consequently, resultant learning ("management decision and technique A results in system change B .") is uncertain; natural resource managers simply do not have complete confidence that their successes or failures are the result of their decisions and actions . Acknowledged uncertainties and imprecise predictions have led the public to conclude that its collective judgement is just as good as the manager's on technical questions.

Changing ethos For the past 40 years the foundation of natural resource value priorities has been undergoing substantial change, driven by resource professionals and their agencies, toward a moral position based on heightened concern for the total environment . As a result, the public is placing more value on components of natural systems and ascribing "rights" for these components to exist . Society is now demanding that natural resources be managed to meet a wider array of values, beyond the previous ethics of either "utilitarian development" or "lock up and reserve" . The new ethic is beginning to influence policy and decision-makers. Many natural resource managers adhere to a view of decision-making which operates according to objective scientific criteria . Some natural resource managers have become fully aware of the importance of ethics in their work and dynamic change in environmental values . After a century of development, today's natural resource manager has inherited an assortment of differing environmental ethical ideals and moral precepts . To traditional resource managers this new polymorphic ethic seems vague, arbitrary, and unrelated to science . They are struggling to function within an acceptable range of social, economic, and ecological conditions while carefully guarding against dramatic changes in direction. The social, economic, and ecological components of natural resources are often managed independently, or only loosely coordinated . These components may be managed by separate agencies in local, State, Native American Tribal or Federal governments . This disjointed, compartmentalized, piece-meal approach to natural resource management is responsible for many persistent and profound environmental and resource allocation problems affecting the Great Lakes .

152

mpedime:nts

Sometimes, an agency's specific responsibilities and management techniques conflict with its broader interests in restoring ecological integrity . Special management considerations for a single aquatic species that occupies a large range will almost inevitably engender conflict with the requirements of other species . Most fisheries managers realize that broader, more long-term objectives are desirable, but are forced to concentrate on game fish because funding and staffing are available to manage these species . One of the major keys to addressing restoration of ecosystem integrity is the provision of adequate funding and staffing to address the task. Many of the methods of problem identification, decision-making processes, and strategies necessary to meet the new, wider array of goals and objectives are outside the narrow discipline of traditional natural resource management. Natural resource managers need to work together and with environmental scientists, economists, and social scientists to: define increasingly intrinsic values and concepts (e .g . ecological integrity) in a structural, functional, and dynamic sense; formulate clear, narrative criteria, based upon scientific principles, that can be used to evaluate the consequences of management decisions on the total range of conditions; address funding and staffing needs ; and apply techniques that can effectively restore and enhance ecological integrity.

Decision-making and public expectations The most pervasive single feature of natural resource decision-making is uncertainty ; ecological, economic, social, and political conditions for decisions are fluid . Where such decisions are well-woven into the social fabric, the task of the resource manager is relatively straightforward . However, when decisions represent a departure from normal practice, or there are two or more competing uses, they are difficult. In the transition to a "values" perspective, policy development and decision-making appear immediately as matters of value arbitration . Values are not objects that can be listed and counted ; a value is, rather, a statement of relationship, an estimation of worth of some object to an individual or in a particular situation . The importance of held values in policy development is recognized by decision-makers and resource managers ; but clear bases for decision-making such as a coherent technical set of concepts to apply, remain elusive . The more complex the environment of policy choice becomes, the more likely it is that decision-makers and natural resource managers will turn to techniques of measurement to provide systematic and uniformly manipulable information; tending to reinforce the primacy of tangible versus inherent values. For example, fisheries managers are increasingly relying on deterministic models as a bases for decision-making. Numerical models, often having unrealistically high data requirements for accurate results, have indoctrinated the minds of many decision-makers and natural resource managers who confuse quantification, objectivity, and sophistication with ecological reality . Many decision-makers and resource managers have become aware of this fact, but the appeal for standardization is strong as are arguments made concerning the relative merits of various methods in relation to negotiability, defensibility, and justification. When different segments of society place competing demands on nature, conflicts are inevitable and often contentious. Interested publics should be involved in developing long-term goals and briefed on rationales and implications during the planning process . Agencies and publics are often prevented from realizing resource potential when special interest groups fail to recognize public trust responsibilities, resource limitations based upon scientific assessment, and the legitimacy and roles of other users .

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Effects of Impediments on Ecosystem Restoration Great Lakes ecosystem restoration A synergistic effect created by a number of factors impedes the restoration of a healthy Great Lakes ecosystem . The introduction of nonindigenous species such as sea lamprey, alewife, and rainbow smelt have altered the fish community . While the latter two species are now considered to be naturalized and important as a forage base for management of the predator stocks, the interaction and potential negative impacts upon other indigenous species needs to be more closely studied . Sea lamprey on the other hand are widely viewed as a nonindigenous species with no beneficial value and continue to exert extensive negative impacts on the fish community . Loss and degradation of critical habitat essential for self-sustaining populations of many fish species has resulted in greater dependence on artificial propagation, or in severe depletion of stocks . Depletion and loss of endemic stocks has degraded the genetic variability necessary for a stable and healthy fish community . Environmental contamination resulting from industrial development within the watershed has resulted in degraded habitat, physiological harm to the inhabitants of the aquatic community, and consumption advisories to the public. Although a great deal of progress has been made in removing or diminishing these impediments, fiscal costs have made the progress slow . Agencies charged with managing and restoring a healthy and stable ecosystem, and its fish community, have been hampered by budget constraints that prevent adequate collection and evaluation of biological information necessary for the development of comprehensive planning . In many cases a lack of technology, or rapidly accelerating costs of technology tend to exacerbate the situation. Lake trout restoration Lake trout are endemic to all the Great Lakes, and have always been among the most valuable components of the fishery, both economically and ecologically . They were driven to extirpation in Lakes Michigan, Erie and Ontario by a combination of sea lamprey predation and commercial fishing . In Lakes Superior and Huron, remnant stocks remained when the sea lamprey control program and stocking of hatchery-reared fish were initiated. Optimism was high that restoration of self-sustaining lake trout stocks would proceed quickly in the 1960s ; however, unforeseen problems prevented the expected progress . Offshore spawning reefs were not re-populated by hatcheryreared fish . Hatchery-reared lake trout often returned to the site of stocking and spawned in these nearshore areas which were unsuitable for survival and incubation of eggs . Renewed interest in harvesting the stocked fish occurred among sport anglers and Native American commercial fishers, who possessed treaty harvesting rights . Nonindigenous forage fish species including alewife and rainbow smelt proved to be unstable when preyed upon by lake trout and introduced coho and chinook salmon. After about three decades of effort, lake trout restoration has made much progress, but remains far from complete. Lessons learned from long and painful experience will be summarized in the proceedings of the 1994 "RESTORE " conference, to be published by the International Association for Great Lakes Research in 1995 . A continued basinwide commitment to lake trout restoration is needed to attain ultimate success.

Examples of Impediments to Restoring a Healthy Ecosystem Inadequate information on fish harvests Fish harvest data are essential for informed management of Great Lakes fishery resources . Harvest data are significant for ecosystem and population management, for social and economic concerns and for planning and evaluation of

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management programs. Harvest monitoring by multiple jurisdictions must be coordinated to be useful in lake-wide management planning. Historically, most harvest on the Great Lakes was taken commercially, and monitored through regular reports by fishermen, and through commercial market records . In recent decades, commercial fishing has declined and recreational fishing has become dominant. Harvest records from recreational fisheries are much less complete . Creel surveys are conducted regularly by some states on some parts of the Great Lakes, but monitoring is of uneven quality due to the inter-jurisdictional nature of the fisheries and inadequate funding in some jurisdictions.

Problems encountered researching the Population Dynamics of Great Lakes Forage Fishes Difficulties encountered in researching the population dynamics of Great Lakes forage fishes included gaining access to databases and detecting changes in data quality . Although a great deal of information has been gathered and catalogued in a formal manner, much has been catalogued only informally . There are five impediments to gaining access to catalogued data for a research study: lag time in publishing data; limited distribution; incompatible storage media; unreadable storage format; and inefficient or inadequate data structure. Many databases consist of a table or tables of numbers, arranged in a logical manner so the user can locate a particular piece of data quickly ; for example, the Bureau of Commercial Fisheries published commercial landings for selected Great Lakes species from 1954 to 1967 . To find the weight of lake whitefish harvested in Lake Michigan in 1967, one simply locates the volume containing records for 1967, identifies the table containing entries for Lake Michigan, and locates the column containing harvests of lake whitefish . The distribution of these published tables is generally restricted to specialized libraries, such as the Van Oosten library at the Great Lakes Science Center or large libraries, such as those at universities. The storage media of the information refers to the physical device or instrument containing the data . In this case, the data are stored on the printed page . Some databases can be stored on microfiche or electronically . Monthly logs from commercial fishers in the Great Lakes have been transferred to microfiche to preserve their integrity and facilitate storage of these detailed records . Since 1971, commercial fishery data have been stored electronically on a minicomputer at the Great Lakes Science Center . The storage medium of the more recent data is computer tape. Databases that are stored electronically can also be characterized by their storage format; in the case of the 1971-1993 commercial fishery database, data have been stored in SAS data set formats . To find the total landings of lake whitefish from Lake Michigan in 1990, the computer tapes containing information on Lake Michigan for 1990 must be located, loaded onto the mini-computer and read electronically. If the user is unfamiliar with SAS or the user's computer cannot read SAS data sets, then a major effort must be initiated to translate the data to another more usable format . Clearly, access to the computer is critical . But the process does not end there . The user must specify (usually via computer code) the information desired, but this requires knowledge of the contents of the database and various other programmatic details .

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One of the greatest technical obstacles to synthesizing historical data is the structure of the database. Even if the user was familiar with software formats and could read these files, there is still no guarantee that the structure of the data would permit extraction of the necessary information (e .g., Fabrizio and Nelson 1994) . This is because the type of information sought must be retrievable in a logical manner . For example, if a user needs to determine catch by species and gear type for each lake in each year, and the catch by species for each lake and year is available, but the type of gear used to harvest each species is not available, then the structure of the data is unsuitable. These examples illustrate that retrieval of information is linked to the distribution, storage medium, storage format and structure of the data . Research studies typically require access to large amounts of data and a great deal of flexibility in working with the data . The printed page becomes an obstacle, and data must be translated to some type of electronic medium . If the data exist on electronic media already, then access to and familiarity with the computer system and appropriate software must be obtained in order to work with the data. Assuming the researcher has found the appropriate database and can read the electronic medium and format, and the structure of the database is such that information can be obtained, then the researcher must carefully assess the quality of the data prior to their use . The quality of the data is highest when the following conditions are met: there is no missing information; the units of measurement for any particular parameter are consistent throughout the database; the same information is recorded in the same manner throughout the database ; and there are no data entry errors. Quality assurance controls must be used to identify inconsistencies, missing information and mistakes . These controls usually require extensive testing of the database, followed by research as to the source of the problem and resolution of the issue . Sometimes inconsistencies can be adjusted and errors can be corrected, but the identification of the problem and follow-up to determine course of action often require much more time than the actual analysis of the data. The time invested in locating, translating, re-formatting and re-structuring databases can be significant, particularly when the database contains information gathered before micro-computers were commonly used (about the mid-1980s) . Thus, just because data have been collected, coded and electronically recorded, doesn't mean the information exists . If it does, it may not be extracted readily or accurately . The saying that we are data rich and information poor' is quite applicable to fisheries databases for the Great Lakes region.

Recent introductions of nonindigenous species Since the 1800s, 139 nonindigenous aquatic organisms have become established in the Great Lakes, including 25 species of fish (Mills et al. 1993) . The rate of introduction has increased ; nearly a third of the organisms were introduced since the opening of the St . Lawrence Seaway in 1959 . The most common mechanisms for entry into the Great Lakes are unintentional releases and ships . The effects of successful nonindigenous species -- defined as reproducing organisms transported by humans to regions where they did not previously exist -- may be instability and unpredictability in previously stable ecosystems, and a loss of diversity in biotic communities (Mills et al. 1993). The impacts of nonindigenous species have been enormous . The sea lamprey has cost millions of dollars in losses to fisheries and in control costs, in addition to the extirpation or severe depletion of lake trout throughout the Great Lakes . The population of alewife grew unchecked by predators after introduction to the Great Lakes, and underwent massive die-offs, polluted shorelines, blocked water intakes and suppressed populations of indigenous chubs, perch and shiners . The pervasive ecological and economic impacts of zebra mussel are still being measured .

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Management agencies are hampered by a lack of technology to control aquatic nuisance species once they have become established . The integrated pest management approach advocated by some requires a set of management tools from which to choose. By and large, these tools do not exist for aquatic pests . The economic injury analysis required by integrated pest management is ill-suited to common property resources and non-economic values such as biodiversity . New analytical and management tools are desperately needed for an adequate response to nonindigenous aquatic nuisance species (Busiahn 1993). Ruffe A fish indigenous to Eurasia, the ruffe was introduced to the Duluth-Superior harbor in the ballast water of an oceangoing ship in the early 1980s (Pratt et al. 1992). This relative of walleye, yellow perch and darters has become very abundant in the harbor and has spread 290 kilometers (180 miles) along the south shore of Lake Superior, through Wisconsin and into Michigan waters . Research indicates that ruffe may be displacing indigenous fishes as its population grows (Ruffe Task Force 1992) . Introduced ruffe populations have also been successful in other waters, such as Loch Lomond, the largest lake in Scotland (Maitland and East 1989). Fish management agencies, anglers and commercial fishers are alarmed at the prospect of ruffe displacing yellow perch or lake whitefish in the Great Lakes and inland waters . Since ruffe were discovered in 1987, a series of task forces and committees has grappled with the difficult question ; what to do? The initial management response by the Wisconsin and Minnesota Departments of Natural Resources was to restrict the taking of baitfish in infested waters, and to attempt to build up predator fish populations by stocking and restricting harvest. A task force appointed by the Great Lakes Fishery Commission issued a.report, Ruffe in the Great Lakes: A Threat to North American Fisheries, and urgently recommended a program of research and control (Ruffe Task Force 1992). Currently a Ruffe Control Committee appointed by the national Aquatic Nuisance Species Task Force is nearing completion of a Ruffe Control Program, the first control program authorized under the Non-indigenous Aquatic Nuisance Prevention and Control Act of 1990. The potential range of ruffe in North America extends from the Great Plains to the eastern seaboard and north into Canada . Prime areas for colonization in the Great Lakes include Lake Erie, Lake St . Clair, Saginaw Bay and Green Bay . If ruffe colonize southern Lake Michigan, they have access to the Mississippi River basin via the Chicago River. Sea lamprey While new introductions of nonindigenous pests are alarming, previous introductions continue to impose enormous costs and impediments to restoring and managing Great Lakes fishery resources . The sea lamprey is a continuing problem in all five Great Lakes, and is an increasing problem in some areas, such as northern Lake Huron and northern Lake Michigan where the effects of uncontrolled St . Mary's River population are most severe. The sea lamprey control program, conducted by the U .S. and Canada through the Great Lakes Fishery Commission, has been very successful in suppressing sea lamprey populations with relatively few side effects ; where conventional piscicide treatments are effective . This very success has bred complacency, as many in the public and in government assume that the sea lamprey problem has been "handled" . This attitude is impeding budget increases necessary to address the St. Mary's River problem . Many of today's managers do not even remember the time when the Great Lakes fishery had been practically destroyed by the sea lamprey, in conjunction with other problems . Rapidly increasing costs have limited program capabilities, even while lamprey populations have increased in areas of improved water quality. Commitment of the U.S. and Canada to sea lamprey control must be maintained . Research on new and refined control techniques must be carried out to reduce dependence on lampricides . New nonindigenous species and other problems must not divert attention from the continuing need for sea lamprey control .

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Schneider, C.P., D.P . Kolenosky, and D .B . Goldthwaite . 1983 . A joint plan for the rehabilitation of lake trout in Lake Ontario. Lake Ontario Committee, Great Lakes Fishery Commission . 50 pages. Schram, S.T., J.R . Atkinson, and D.L. Pereira. 1991 . Lake Superior walleye stocks : status and management . Pages 1-22 in P.J. Colby, C .A. Lewis, and R.L. Eshenroder (ed.) Status of walleye in the Great Lakes : case studies prepared for the 1989 workshop . Great Lakes Fishery Commission Special Publication 91-1. Schram, S.T., T .L. Margenau, and W .H. Blust . 1992. Population biology and management of walleye in western Lake Superior. Wisconsin Department of Natural Resources Technical Bulletin 177 . 28 pages. Schrouder, K ., J.P. Baker, and M .P. Ebener. 1994. Status of warmwater fishes in 1992 . Pages 65-68 in M.P . Ebener, (ed .) The state of the Lake Huron fish community in 1992 . In review. Scott, W.B . and E .J. Grossman . 1973 . Freshwater Fishes of Canada . Fisheries Research Board of Canada Bulletin 183 . Ottawa, Canada 966 pages. Seelbach, P.W. 1985 . Smolt migration of wild and hatchery-raised coho and chinook salmon in a tributary of northern Lake Michigan . Michigan Department of Natural Resources, Fisheries Research Report 1935, Ann Arbor, Michigan. Seelbach, P.W. 1986. Population biology of steelhead in the Little Manistee River, Michigan . Doctoral Dissertation, The University of Michigan, Ann Arbor, Michigan. Selgeby, J .H. 1982. Decline of lake herring (Coregonus artedit) in Lake Superior: an analysis of the Wisconsin herring fishery, 1936-78 . Canadian Journal of Fisheries and Aquatic Sciences 39 :554-563. Selgeby, J .H . 1985. Population trends of lake herring (Coregonus artedii) and rainbow smelt (Osmerus mordax) in U.S. waters of Lake Superior, 1968-84. Pages 1-12 in R.L. Eshenroder (ed.) Presented papers from the Council of Lake Committees Plenary Session on Great Lakes Predator-prey issues, March 20, 1985 . Great Lakes Fishery Commission Special Publication 85-3. Serchuk, F .M., and R .J. Smolowitz . 1990 . Ensuring fisheries management dysfunction : the neglect of science and technology. Fisheries (Bethesda) 15 (2) :4-7. Shupp, B . 1994 . Issues facing traditional fisheries management . Fisheries (Bethesda) 19(4) :24-25. Skud, B.E. 1982 . Dominance in fishes : the relation between environment and abundance. Science 216 :144-149. Sluka, R .D. 1991 . The effects of spring climate, spawner abundance, and cannibalism on the abundance of rainbow smelt (Osmerus mordax) at two sites in the upper Great Lakes . M.Sc. Thesis, Department of Fisheries & Wildlife, Michigan State University, 60 pages. Sly, P.G. and W.-D .N. Busch . 1992 . A System for Aquatic Habitat Classification . Pages 15-26 in W .-D .N . Busch and P .G . Sly, (eds.) The Development of an Aquatic Habitat Classification System for Lakes . CRC Press, Boca Raton, Florida. Sly, P .G. and W .-D .N. Busch. 1992 . Introduction to the process, procedure, and concepts used in the development of an aquatic habitat classification system for lakes . Pages 1-14 in W .-D .N. Busch and P .G. Sly, (eds .) The Development of an Aquatic Habitat Classification System for Lakes . CRC Press, Boca Raton, Florida. Smith, S .H. 1956 . Life history of lake herring of Green Bay, Lake Michigan . U.S. Fish and Wildlife Service, Fisheries Bulletin 57 :87-138.

Smith, S .H. 1964. Status of the deepwater cisco populations of Lake Michigan . Transactions of the American Fisheries Society 93 :155-163.

Smith, S .H . 1968 . Species succession and fishery exploitation in the Great Lakes . Journal of the Fisheries Research Board of Canada 25(4) :667-693 .

170

References r

Smith, S .H. 1970 . Species interactions of the alewife in the Great Lakes . Transactions of the American Fisheries Society 99 :754765. Smith, S .H. 1972 . Factors of ecologic succession in oligotrophic fish communities of the Laurentian Great Lakes . Journal of the Fisheries Research Board of Canada 29 :717-730. Smith, B .R., J.J . Tibbles, and B .G.H. Johnson . 1974 . Control of the sea lamprey (Petromyzon marinas) in Lake Superior, 19531970 . Great Lakes Fishery Commission Technical Report 26. Smith, B .R. and J.J. Tibbles . 1980. Sea lamprey (Petromyzon marinas) in Lakes Huron, Michigan, and Superior : History of invasion and control, 1936-78 . Canadian Journal of Fisheries and Aquatic Sciences 37 :1780-1801. Smith, G .R., and T.N. Todd. 1984. Evolution of species flocks of fishes in north temperate lakes . Pages 45-68 in A. A. Echelle and I . Kornfield (ed.) Evolution of fish species flocks . University of Maine Press, Orono Maine. Smith, C . Lavett. 1985. The inland fishes of New York State . New York State, Department of Environmental Conservation, Albany, New York . 522 pages. Sprules, W.G., S.B. Brandt, D .J. Steward, M . Munawar, E .H. Jin, and J . Love. 1991 . Biomass size spectrum of the Lake Michigan pelagic food web . Canadian Journal of Fisheries and Aquatic Sciences 48 :105-115. Stewart, T .W. and J.M. Haynes . 1994 . Benthic macroinvertebrate communities of southwestern Lake Ontario following invasion of Dreissena . Journal of Great Lakes Research . 20(2) : 479-493. Stone, J .N., and Y . Cohen. 1990 . Changes in species interactions of the Lake Superior fisheries system after the control of sea lamprey as indicated by time series models . Canadian Journal of Fisheries and Aquatic Sciences 47 :251-261. Swanson, B .L. and D.V. Swedberg. 1980. Decline and recovery of the Lake Superior Gull Island reef lake trout (Salvelinus namaycush) population and the role of sea lamprey (Petromyzon marinas) predation . Canadian Journal of Fisheries and Aquatic Sciences 37 :2074-2080. Talhelm, D .R. 1987 . Recommendations from the SAFR (Social Assessment of Fisheries Resources) Symposium . Transactions of the American Fisheries Society 116 :537-540. Taylor, W.W., M.A. Smale, and M.H. Freeberg. 1987 . Biotic and abiotic determinants of lake whitefish (Coregonus clupeaformis) recrutiment in northeastern Lake Michigan . Canadian Journal of Fisheries and Aquatic Sciences 44 (Suppl . 2) :313-323. Testa, W .A. (ed.). 1991 The Great Lakes Economy: Looking North and South . Federal Reserve Bank of Chicago, Chicago, Illinois. 163 pages. Thorp, S.J. and A .G. Ballert . 1991 . The Great Lakes regional transportation system . Pages 85-96 in W.A . Testa, (ed .) The Great Lakes Economy: Looking North and South . Federal Reserve Bank of Chicago, Chicago, Illinois . 163 pages. Thorp, S.J. and S.L. Smith. 1991 . Travel, tourism and outdoor recreation in the Great Lakes region . Pages 117-127 in W.A. Testa, (ed .) The Great Lakes Economy: Looking North and South . Federal Reserve Bank of Chicago, Chicago, Illinois . 163 pages. Todd, T .N. and Smith, G .R. 1992 . A review of differentiation in Great Lakes ciscos . National Fisheries Research Center-Great Lakes and the Museum of Zoology, University of Michigan, Ann Arbor, MI . Pages 261-267. Tody, W.H ., and H .A. Tanner. 1966 . Coho salmon for the Great Lakes . Fish Management Report No . I. Fish Division, Michigan Department of Natural Resources, Lansing, Michigan. 38 pages. Trandahl, A.J., J.K. Anderson, S .E. Hood, R .L. Scholl, W.F. Shepherd, A .J. Stoltz and H . VanMeter . 1975 . Blue pike recovery plan, prepared for the survival, protection, and enhancement of an endangered species . Blue Pike Recovery Team . October, 1975. Trautman, M .B. 1981 (revised) . The fishes of Ohio . Ohio State University Press . 782 pages.

171 References'.

Upper Lakes Reference Group . 1976. The waters of Lake Huron and Lake Superior . Volume 1, Summary and recommendations. Report to the International Joint Commission. Upper Lakes Reference Group. 1977 . The waters of Lake Huron and Lake Superior, Volume 3, Parts A and B . Report to the International Joint Commission. U.S. Department of the Interior, Fish and Wildlife Service and U.S. Department of Commerce, Bureau of the Census . 1991 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation . U.S . Government Printing Office, Washington, D .C. 1993. Van Meter, H .D . and M .B Trautman. 1970 . An annotated list of the fishes of Lake Erie and its tributary waters exclusive of the Detroit River . The Ohio Journal of Science 70(2):65-78. Van Oosten, J . 1937. The dispersal of smelt, Osmerus mordax (Mitchill) in the Great Lakes region . Transactions of the American Fisheries Society 66 :160-171. Van Oosten, J .R., R . Hile, and F .W. Jobes . 1946 . The whitefish fishery of Lakes Huron and Michigan with special reference to the deep trapnet fishery . U.S . Fish and Wildlife Service, Bulletin 40 :279-394. Van Oosten, J . 1947. Mortality of smelt, Osmerus mordax (Mitchill), in Lakes Huron and Michigan during the fall and winter of 1942-1943 . Transactions of the American Fisheries Society 74 :310-337. VoIlenweider, R .A., M. Munawar, and P . Stadelmann . 1974 . A comparative review of phytoplankton and primary production in the Laurentian Great Lakes . Journal of the Fisheries Research Board of Canada 31 : 739-762. Walker, S .H. 1992 (draft) . Status of the lake sturgeon in the upper Great Lakes. U.S . Department of the Interior, Fish and Wildlife Service, East Lansing Field Office . 23 pages. Waters, T .F. 1987 . The Superior North Shore . University of Minnesota Press, Minneapolis . 361 pages. Webster, D.A. 1982 . Early history of Atlantic salmon in New York . New York Fish and Game journal, 29(1) . 44 pages Wells, L ., and A . L. McLain. 1972 . Lake Michigan : Effects of exploitation, introductions, and eutrophication on the salmonid community . Journal of the Fisheries Research Board of Canada 29 :889-898. Wells, L ., and A . L. McLain. 1973 . Lake Michigan: man's effects on native fish stocks and other biota . Great Lakes Fishery Commission Technical Report. 20. 56 pages. Whaley, H .P. 1991 . Non-fuel mineral resources . Pages 107-109 in W.A. Testa, (ed .) The Great Lakes Economy : Looking North and South. Federal Reserve Bank of Chicago, Chicago, Illinois . 163 pages. Whillans, T .H., R .C . Smardon, and W.-D .N. Busch . 1992 . The state of Lake Ontario wetlands . Great Lakes Research Consortium, State University of New York, College of Environmental Science and Forestry, Syracuse, New York . 53 pages. Williams, J .E., J.E. Johnson, D .A Hendrickson, S . Contreras-Balderas, J .D . Williams, M . Navarro-Mendoza, D .E. McAllister, and J.E. Deacon. 1989. Fishes of North America, endangered, threatened, or of special concern . Fisheries, Bethesda 6(1) :2-20. Zuboy, J .R. 1981 . A new tool for fishery managers : the Delphi technique . North American Journal of Fisheries Management 1:55-59 .

g

172

Glossary

Glossary biota the living components of habitat, including plants and animals. EPA U.S. Environmental Protection Agency. habitat the sum total of the physical, chemical and biological attributes of a specific location, which constitutes a distinct fish or wildlife refuge, feeding site, or breeding location. nearshore sub-system all coastal features, as well as islands and shallow water features such as reefs and shoals. beach the zone of unconsolidated material, or debris, between the low water mark and the bottom of the cliff. coast the zone landward of the base of the cliff, with the line of demarcation known as the coastline. shore that zone, from the low water mark landward to the base of the cliff, large or small, which marks the landward limit of effective wave action (cliff, in this sense, refers to the abrupt change in gradient, no matter how small, indicating where wave erosional forces cease, and is usually demarcated by a change in vegetation and substrate). open water sub-system includes circulatory basins and extends shoreward, to either the sand/silt sediment boundary or the attached plant boundary, whichever reaches the greater depth. impairments to habitat stresses which interfere with normal life processes of organisms living within a specific habitat unit. introduction intentional import or introduction of nonindigenous species into, or transport through, an area or ecosystem where it is not established in open waters for a specific purpose such as aquaculture, aquarium display, or fishery enhancement (stocking). unintentional introduction of a nonindigenous species that occurs as a result of activities other than the purposeful importation, transport, or introduction of that species .

173

Glossary ` :,';;.

nonindigenous species any species or other viable biological material that enters an ecosystem beyond its historic range. PCB poly-chlorinated biphenyl compound. rehabilitation altering an ecosystem to restore elements of structure, function, diversity, and dynamics without necessarily attempting complete restoration to specified prior conditions. restoration the reestablishment of self-sustaining populations of fish and wildlife . It may involve enhancement and/or rehabilitation of the structure, function, diversity, and dynamics of the biological system. TFM the selective sea lampricide, 3-triflouromethyl-4-nitrophenol. trophic guild herbivore greater than 75 percent of the diet consists of plants from substrate (diatoms and blue-green algae associated with substrate) and vascular plants. omnivore diet consists of at least 25 percent plant and equal to or greater than 25 percent animal material. planktivore greater than 75 percent of the diet consists of zooplankton and/or phytoplankton. carnivore piscivore greater than 75 percent of the diet consists of fish. macroinvertivore greater than 75 percent of the diet consists of macroinvertebrates (insects, crustaceans, annelids, etc .) veliger the free-swimming larval stage of the zebra mussel (for the purposes of this report) .

174

Appendix;

Summary of Recommendations

Recommendation

Period

i

Develop and Adopt Aquatic Community and Habitat Goals and Objectives to Support Ecosystem Management

Multi-year

2

Fully Implement the Strategic Plan for Management of Great Lakes

Multi-year

Fisheries

3

Conduct Comprehensive and Standardized Ecological Monitoring

Multi-year

4

Standardize Fish Community Assessment Data and Establish Comprehensive Fishery Databases

Multi-year

5

Develop Offshore Capabilities

One-time

G

Fish Community Assessment Program

Multi-year

7

Fish Community Modelling

Multi-year

8

Coordinate State and Native American Tribal Harvest Monitoring and Management: Measure Commercial and Recreational Fish Catches

Multi-year

9

Evaluate Ecological Effects of Stocking and Revise Stocking Strategies, as Necessary, to be Consistent with Proposed Aquatic Community and Habitat Goals and Objectives

umbers are included for reference only and do not indicate priority.

Multi-year

175

Summary of Recommendations

Recommendation

Period

10

Ecological Information ClearinghouselGeographic Information System

Multi-year

11

Identify, Inventory, Protect and Rehabilitate Significant Habitats

Multi-year

12

Develop and Implement Action, Restoration and/or Enhancement Plans for Exploited, and/or Declining Indigenous Aquatic Species

Multi-year

13

Develop and Implement Action/Restoration Plans for Forage Fish

Multi-year

14

"Close the Door" on Nonindigenous Species Introductions

Three years

15

Implement and Expand Effective Sea Lamprey Control

Multi-year

16

Great Lakes Fishery Commission Line Item Funding for Sea Lamprey Control Efforts in the St . Mary's River

Multi-year

17

Fund Implementation of the Great Lakes Fishery Commission's Basin-wide Sea Lamprey Barrier Plan

Multi-year

18

Prevent or Delay the Spread of Ruffe Multi-year

19

Determine the Impacts of Hydroelectric Facilities and Dam Operations on Fishery Resources

Numbers are included for reference only and do not indicate priority.

Three years

176

Appendix

Summary of Recommendations

Recommendation

Period

20

Increase Involvement in the Binational Program to Restore and Protect Lake Superior and Expand this Mechanism to Lakes Huron, Erie, and Ontario

Multi-year

21

Establish Uniform Tissue and Sediment Contaminant Levels Used by Various Agencies for Ecosystem Health

Two years

22

Broaden the Scope of Current State Antidegradation Policies, Regulations, and Strategies

One year

23

Develop and Implement an Action Plan to Analyze Contaminant Level Effects on Aquatic Resources

Multi-year

24

Participate in Remedial Action Plans, Lake-wide Management Plans, and the Environmental Monitoring and Assessment Program

Multi-year

25

Salmonine Egg Viability

Multi-year

26

Establish an Isolation or Quarantine Facility

One year

27

Develop an Epizootic Epitheliotrophic Disease (EEDV) Diagnostic Test

Two years

28

Fish Health Multi-year

Numbers are included for reference only and do not indicate priority.

177

Summary of Recommendations

Recommendation

Period

29

Fish Genetics

Multi-year

30

Lethality of Sea Lamprey Attacks

Three years

31

Develop Aquatic Resource Education Programs

Multi-year

32

Conduct a Cormorant Fishery Predation Study

Three years

Numbers are included far reference only and do not indicate priority.

These recommendations address issues common to all five of the Great Lakes and their watersheds and identify priorities not currently funded through any of the agencies, but considered essential to meet the Fish Community Goals and Objectives for each of the Great Lakes . Funding necessary to accomplish some of these tasks would be provided to the partners on an equal cost-share basis by the Service, as funds become available . Funding of projects would be accomplished based upon priorities established via a multi-agency committee project approval process to be developed by the Service, the Great Lakes Fishery Commission, the State and Native American Tribal partners, and other interested parties. All recommendations assume the effective establishment of the aforementioned project approval process, are not limited to funding through or implementation by the Service, and rely heavily on input from and future cooperation among Great Lakes Basin partners . It is expected that future projects addressing these recommendations will focus first on implementation where information is sufficient and on data collection where information is lacking.



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COMMON NAME

SCIENTIFIC NAME

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SCIENTIFIC NAME

COMMON NAME

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us Notropis volucellus Opsopoeodus emiliae Phenacobius mirabilis Phoxinus eos Phoxinus erythrogaster

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Coregonus artedii

Coregonus clupeaformis Coregonus hoyi Coregonus johannae Coregonus kiyi Coregonus nigripinnis Coregonus reighardi

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b

Esox niger

Umbra limi Osmerus mordax

SR :s?

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Current status is identified by lake as follows: X = Extinct, E = Extirpated, R = Rare, C = Common, A = Abundant, Black = No Occurrence, Shaded = Unknown. Current trend is identified by lake as follows : Arrow down = Decreasing, Diamond = Stable, Arrow up = Increasing, Black = No Occurrence, Shaded = Unknown. An asterisk (') indicates nonindigenous.

446 4 J J Jy

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COMMON NAME

SCIENTIFIC NAME

Pink salmon Coho salmon Rainbow trout

MIM :c MINEEIMMIl

LAKE SUPERIOR LAKE MICHIGAN LAKE HURON Status Trend

R

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Morone americana Morone chrysops

is

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Morone mississippiensis Morone saxatilis Lepomis aurltis Lepomis cyanellus

C

A

Ambloplites rupestris

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X

J

F

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1

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Fantail darter Least darter Johnny darter

1 ~

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Etheostoma flabellare lineolatu Etheostoma microperca Etheostoma nigrum

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r t,vr-)~riCi7'. ;ititi ? . :`y r"y-'SiJiiryn ` :,r'%.v4{7.4\~j•' ' }} . . .Y?tip ,v. :5-i}. ! . } . .r.` .q)x.:S :,`Vf'`;`'r; : ;> • :r?. ~); );a:..}+\~c ti :¢: .r~r;a : {n?:Ct~:.:. >.. ,Y . ..: .,. x : v c 'gag; ra il`f °:rte'':°:."



COMMON NAME

SCIENTIFIC NAME

Tessellated darter Orangethroat darter Banded darter

Etheostoma olmstedi Etheostoma spectabile Etheostoma zonale

LAKE ONTARIO LAKE SUPERIOR LAKE MICHIGAN LAKE HURON LAKE ERIE Status Trend Status Trend Status Trend Status Trend Status Trend yr

A

Freshwater drum Round goby Tubenose goby

C

A

BIM:~.

EMI MOM ?

Percina maculata Percina phoxocephala Percina shumardi 1

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^>

4

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